Black93lt1

I have a 93 lt1 that normally idles at 1k rpms and right now it is jumping up to 2k and 1.5k at idle it will also drop down to 500 and try to die....what's wrong???

Injuneer

Manual or auto trans? RPM is controlled by the ECM (computer). Stock for the M6 is 800 RPM, stock for the A4 is 550 RPM in gear and 650 RPM in neutral. The tach typically seems to read 100-200 RPM higher than actual engine speed. That is based on a fully warmed up engine.

I'd start by scanning ot for codes:

http://shbox.com/1/dlc2.jpg

Then check for vacuum leaks.

ECM controls the idle by moving the idle air control valve in the base of the throttle body. It would be interesting to see how the ECM IAC "counts" respond to the high and low idle. You can scan the ECM with TTS Datamaster.... free download, 20 free uses before it asks you to buy a license.

TTS Power Systems

Black93lt1

I was reading up in different places and one brought up the IAT sensor and be4 after replacing the distributor I started her up with out the air intake attached and she idled great but was really rich and when I did it be4 I had attached the sensor and figured I would check it out so I took the sensor off and now idles great but is running really rich

Injuneer

Your 93 uses "speed-density" to calculate the air flow into the engine. It needs an accurate air temperature to make the calculation. Did you disconnect the IAT sensor? If so, it reads an infinite resistance which means a very low temperature = very dense air. That will cause the engine to run rich. It should also set a code.