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Discussion Starter #1
My car recently started to have a hanging idle problem. I've done a done a ton of searches, but it looks like IAC/TPS, and or vacuum issues should be the problem.

Here are the symptoms: Upon first starting the car and driving for ~10-15 minutes, it behaves fine. I suspect that it is because it is in closed loop at this point. At some point in time as I let off the gas, the idle will hang anywhere between 1500-4000 rpm. If I blip the throttle hard enough, it will "catch" and come back down to the normal 800 idle speed.

It also always comes back down to 800 when I come to a stop.

Here is what I've tried thus far:

I've used my DSP to monitor TPS voltage, and it appears that when I let off the gas, the voltage still reads at 1.1+ volts. (.69 +-) is where it sits when everything is behaving properly. Once it settles down, it goes back down to the expected range.

I put in a brand new IAC and that did not fix the issue. I've since returned that new sensor and put the old one back in.
I emptied my catch-can and cleaned out the PCV.
I did a boost leak test.
I sprayed brake cleaner all around the vac lines and IM but didn't find anything.
I did a TPS re-wire about 2 years ago for preventative maintenance.

Sometimes when I pull into my garage after it was hanging, it will continue to hang around 1300 rpm. If I jiggle the IAC/TPS wires, there is no change.

Another thing I've noticed is that when it's really hot out, it seems to hang worse. Note that I installed a N2MB wot/2step several years ago.

If it were a vacuum leak, wouldn't it idle high at all times?

If it were a TPS/IAC issue, would the idle change when you wiggle the wires?
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