Need opinions on fixing my pickup...

[R Q]

97 Chevy, 2500HD, 5.7. 4L80E, A/T, 2wd 183K

recent tuneup with plugs wires, cap, button,. Still runs like crap at idle and up to 2000 rpm. Had the codes ran at Autozone and and had two come up, P0172
Definition:
Fuel trim bank one condition
Explanation:
The powertrain control module use the O2 sensor to calculate the Air/fuel ratio of the engine. The computer has recognized a rich or lean condition on one engine bank only.
Probable cause:
1.If bank one and two codes set together suspect fuel pressure or MAF Sensor
2. O2 sensor defective
3. Ignition Misfire-repair
4. Fuel Injector problem

And then code PO175
Fuel bank two condition
ECM has detected a rich or lean condition on bank two
Cause;
1. Suspect fuel pressure or MAF
2. Failed H02821 (heated O2 sensor) bank 2
3. Injector problem
4. Engine Mechanical condition.

I have gauges to check fuel pressure and will do that in the morning.
Its been stumbling at low idle for a long time. I've replaced all O2 sensors before but it's been 75k ago. I read about the distributors having a plastic part that wears out and causes this issue. I replaced the fuel injectors (spider) was what they called it at about 75k.
The cats are gutted.
I don't have money to throw parts at it. I can switch out the MAF with another truck I have to check it.
Any help is appreciated.
RQ

 

[RHSCTJ]

Maybe vacuum leak? Spray carb cleaner around the base of the intake, see if it stumbles.

 

[AX(J)15_tudor]

A walk through I found for this situation. Good news is you can test the fuel pressure, and you have a maf too to test with you said. That's 2 of the bigger items hopefully you'll get lucky and isolate it that way.
If you know someone or a reasonable mechanic with a really good scanner you can probably get it figured out and not throw parts at it. Another poster was having multiple issues with his 6.0 and after asking around he had his mechanic with a good scanner figure out it was fairly minor (spark plug iirc) and quickly compared to the time he had spent messing with it at home.

What Are Some Common Causes of Code P0172/P0175?
Always check to make sure that there is not a PCM software update due or available. Often, as the vehicle's engine wears, the PCM's Fuel Map software inaccurately compensates for this condition. The fuel mixture grows rich and eventually, the code sets.
An "over reporting" Mass Air Flow Sensor can be a common cause of a code P0172 and P0175. Essentially, this means that the Air Flow Sensor is telling the computer that much more air is entering the engine than actually is. Based on this large amount of air entering the engine, the engine computer or PCM sprays more fuel into the combustion chambers.
Since the oxygen sensors are telling the computer that less fuel is needed, this causes confusion in the computer because the Mass Air Flow Sensor is still saying there is too much air and the Oxygen Sensor is reporting that the mixture is still too rich. The computer tried to compensate, but since resolution is impossible, it sets the code. It is important to restate that the Oxygen Sensors are accurate—the fuel mixture is too rich. In this case, the Air Flow Meter or Sensor is inaccurately reporting the real amount of air entering the engine.
How Do I Know if the Problem Is the Mass Air Flow Sensor?
There is a very effective "truth test" for any Mass Air Flow Sensor. Start the engine, let it idle, and then check the Barometric Pressure reading on the scan tool data. If the reading is about 34.5 Hg and you are close to sea level, you know that you have a defective Air Flow Meter because it is telling you that you are at about 4000 feetbelow sea level. (These conversion tables will help.) When the Mass Air Flow Sensor sees this Barometric reading, it adjusts its Air Density table and then "over reports" the actual amount of air entering the engine. It does this because the Barometric Pressure Sensor is actually part of the Mass Air Flow Sensor.
Sometimes the Air Flow Sensor and the sensing wire get covered with dirt, dust, or oil residue, which can also set a P0172. Cleaning the sensor might hold off problems for a while, but eventually, the MAF sensor should be replaced. Always make sure the Air Filter and its enclosure are dirt-, dust-, and oil-free. If you clean and replace the filter and its enclosure as needed, you will prevent the new MAF from failing.
Additional Causes of Code P0172/P0175

• Defective Manifold Absolute Pressure (MAP) Sensor and/or its vacuum line. Check the MAP reading and then do a manual vacuum reading. An engine needs to have at least 17 to 18 inches of vacuum in order to run properly. When the MAP reading is low, the PCM thinks that the vehicle is under heavy load and increases the fuel supply.
• Mechanical engine problems will cause a low MAP sensor reading because engine vacuum is low or erratic. A slipped or inaccurately installed Timing Chain or Timing Belt and/or leaking Head Gasket can cause poor vacuum and MAP readings. If the engine has a mechanical misfire from valve train problems or weak cylinder compression, it will send puffs of oxygen into the exhaust system. This will cause the Oxygen Sensors to receive false "lean" readings (high exhaust oxygen content).
• A defective Oxygen Sensor can sometimes cause a P0172. If the Oxygen Sensor heater element only works intermittently—well enough to pass the readiness test, but fails once the car has been driven for a while—the vehicle will go into "open loop."
• A stuck Fuel Pressure Regulator can cause a rich condition since the Fuel Pressure will be too high, causing an "over fueling" condition. Be sure to verify proper Fuel Pressure under various driving conditions.
• An inaccurate Coolant Temperature or Air Temperature Sensor can cause a rich condition because they will report that the engine is still cold, which will cause the PCM to keep the mixture rich long after the engine is at proper operating temperature.
• A Thermostat stuck in the open position can mechanically cause a code P0172, especially in cold climates. The engine won't warm up, preventing it from going into "closed loop" fuel control.
• Ignition misfires, like mechanical misfires, cause puffs of oxygen to keep hitting the Oxygen Sensors. Since the sensors will think the mixture is running lean, the PCM will add fuel to the mixture.
• A worn or stuck wiper in the Throttle Position Sensor will tell the PCM that more power is being requested by the operator. The PCM will add fuel to accommodate this false TPS reading.
• If the vehicle is not hoisted properly, the fuel return line can be pinched, causing a high Fuel Pressure condition. Always verify Fuel Pressure for any code P0172.
• Shorted Fuel Injector windings can cause the injectors to spray too much fuel, causing a rich condition. Be sure to verify the Pulse Width (the PCM "on" time) with the Labscope Injector Firing pattern. Be sure to "Ohm check" the injector winding resistance as well in order to verify that it's within specification.