95 Tahoe Surging problem

[WyomingTahoe]

I just replaced my TPS and IAC a while back, and now I'm having a surging problem at idle. I'm also getting terrible gas mileage. Here's a list of things done within 40,000 miles of putting in the new engine.

• MAP sensor replaced
• O2 sensor replaced
• Catalytic Converter & muffler replaced
• Both coolant temp sensors replaced
• Spark plugs, distributor cap, rotor, and wires replaced
• TPS & IAC replaced
• Fuel pump replaced with engine, fuel filter replaced 5,000 miles ago
• AC System: compressor, condenser, sensors all replaced
• Transmission fluid, all filters in engine and transmission

Most of top end has not been replaced other than mentioned. The car has 203,000 miles. Any body think they know what the problem is?

 

[lesterl]

Pull the EGR off and clean it or block it off, test drive.

 

[lesterl]

ONLY REPLACE WITH OEM unit, no aftermarket as it will be worse.....

 

[Jaybiz1980]

I have a 95 with a 5.7 tbi. Completely rebuilt andand 4l60e trans also completely rebuilt. I have the same problem or I should had. I replaced everything all vacuum and solenoids. Fuel regulator and what not. I diddnt replace my egr right away because it pushed in smoothe with no binding. When I un plugged it from the solenoid and got on the highway the check light came on but it ran like a dream. Plug it in and bogged down again. It should be the other way around. But I replaced it and it fixed it

 

[lesterl]

Spring gets weak inside them, or they get carboned up and wont shut all the way off....

 

[Jaybiz1980]

Thats what I discovered when I replaced it. It wasn't binding up or anything but because it had 260k on it the carbon buildup made a ring and it wouldn't shut all the way. What baffles me is why would the engine run better with it dissabled.

 

[lesterl]

The EGR allows exhaust gas to recirculate, it is usually only enabled during a highway drive at highway speeds so you wont notice the running, The EGR serves to cool the combustion so more timing advance can be used, it helps in other ways as well. At an idle the extra airflow is unneeded and uncalculated causing an imbalance.