I finally solved an erratic high idle problem that I have been having for sometime. Stock '87 305 TPI, A4; Symptom - Ocassionally, after start-up and stopping at lights / stop signs, the engine would idle high (1500 RPM) and then come back down to a normal idle. I connected my laptop and used TunerPro to scan data. When the idle started to go high, I noticed the IAC steps going up slowly (as assumed / predicted). I also noticed my TPS voltage going up slightly as well.

In a nut shell, the TPS voltage that was creeping up, made the IAC steps increase, thus increasing my idle. Previously, I had replaced the TPS for preventive maintenance. My TPS connector / pigtail looked pretty boogered up too (original connector), so I bought a new TPS pigtail and went back to my OE TPS sensor (reset TPS voltage) and the idle is now back to normal. It is amazing how a high idle can drive you crazy! Not only knowing that something is wrong, but the drivibility of the vehicle stinks. Now, it is so much pleasurable to drive.

CG