Quoting AnotherNewb:
The nub you are talking about is supposed to be touching the buttryfly pulley. When the throttle is closed, The connector on top should be grounded. I don't believe it is the cause of your high idle. Since it stays steady I would make sure that the engine fully comes up to temperature that will eliminate a thermostat causing the car to stay in high idle mode. Next be sure that there are no major vacuum leaks, a boost leak test will help greatly there. If you still can't find it my next move would be to block off the fiav. Only things I can really think of that would cause high idle but not idle surge.
disconnecting mine drastically increases my idle.
I have a few questions for you though.
1. is your coolant still run through your throttle body? - this would be a FIAV issue
2. is your coolant temps still plugged in? check the sensor make sure it is properly hooked up. if a ground falls off, this will cause your idle to increase also. NOTE: even if your guage temp is working, this does not mean the ecu is recieving a signal from the coolant temp sensor
3. DEF check the TPS. even though I found this doesn't usually result in an increase of 2000 rpm, still very important.
4. Do you have an A/F gauge? if not hook up a volt meter to your 02 sensor. At idle when your car is warm, it should be running from lean to rich (roughly 0 to 1v) oscillating between the two. All of the above will cause the car to run rich, raise the idle, and the 02 sensor will tell that by just giving a reading close to 1v, and being relatively steady.
if all else fails, check for a boast leak. The FIAV should be blocked off if it hasn't been and no coolant is running through it...even if there is coolant. After 20 years they begin to fail. Also I have heard of the coolant temp sensor failing, resulting in this issue.
the engine uses a combination of the engine temperature, TPS, and the switch that is an on/off, it was mentioned above. it is hit when the u release the throttle. Lastly the ecu uses hte MAF to know the air coming in to achieve a low smooth idle. ANYTHING affecting the above will mess with your idle.
hope this helps! i've been through hell and back w/ this issue...i'm pretty sure it's a right of passage in order to own one of these cars.