Okay, now I have a different problem. I have a 1996 coupe auto. Changed my injectors with ones from FIC. Fit great and wasn't hard to do. Now I have 2 other problems. I decided to clean my IAC (P0507 code) and throttle body without taking off the throttle body. Took off the IAC, sprayed with throttle body cleaner and screwed back in. Then sprayed inside the throttle body until clean. I accidentally took off the TPS thinking it was the IAC so I re-installed it. I took it for a drive and my rpms were at about 2500 when I started it. Drove around on the highway and rpms stayed around 2500 and was about 1500 in gear. I got home and took off the IAC again. Noticed that the little gasket was broken and also the pintel and spring don't move when I push down on it. Not sure if the gasket or pintel/spring might be the problem. I also removed the TPS again and it looked fine. 1. by the description of my IAC, does it need to be replaced? 2. Is the idle high because I didn't "reset" the IAC before driving? 3. If it's the TPS, is there a way to adjust it or is it self adjusting for my year? 4. I noticed that the orange, spongy gasket for the TPS needs to be replaced. Does it come with a new TPS or where can I buy it? It seems like I've been fixing and replacing something every time I open the hood. With the idle problem, I can't tell how well the Bosch injectors are working. Thanks in advance, Ed.

 

With idle that high you definitely have a vacuum leak.

The pintle of the IAC is moved by a stepper motor. You don't need to know what that is, but the pintle should be hard to move. I can get mine to retract by pressing it against my workbench. I can't push it in with my fingers. The PCM calibrates the IAC when you start the engine, so there is no need to do anything there. One thing that can happen is that the pintle is extended too far when you install it. If that happens it can bottom out in the bore before the IAC is completely screwed in and break the plastic guide the pintle rides in (Been there. Done that on a brand new IAC.).

The TPS is not adjustable on LT engines. The ECM reads the output when you turn on the ignition and calls that "idle". It should read about 0.7 volts at idle or when the engine is off (much easier to measure without injuring yourself when the engine is off...).

I don't know anything about "orange, spongy" gaskets. My TPS works off the end of the throttle shaft and there is no gasket. Maybe your setup is different than my L98.

 

Having a broken IAC gasket would allow unmetered air into the engine causing high idle , replace the gasket on the IAC , these are available in a kit from Advance Auto...If you just take the IAC out, and then replace it, you shouldn't have to retract the pintle because it didn't move, just screw it back in..They also suggest putting a drop of oil on the pintle to lube it before reinstalling it....WW

 

I agree to repair the gaskets first and then see what you have. As said if air is being sucked in it will cause a high idle.

Decades ago I use to really clean and lube the IAC, and move around the pintle. I don’t do that anymore. I never had any luck cleaning them if they were defective. You can also damage some IACs by moving or forcing the pintle in and out.

All I ever do these days is to clean the pintle and anything I can just wipe off. If I think is bad, I get a new one.

Fix known problems first, then evaluate if necessary.

 

I agree with WW. The IAC controls air flow at idle and if air is leaking around the gasket your idle will increase.

Sounds like you have my luck. Fix one thing and break two.

Good Luck!