Hey guys I recently purchased a 1991 N/A FC Coupe with 66k miles. It had an overheating issue but I fixed it by having the thermostat, water pump, and coolant changed.

My next thing to fix is the idle issue. When I start the car, it goes to 2k rev and stays there until the car is hot and continues to stay there. After driving for like 5 minutes the car goes to about 1.2-1.5k but not much lower. My friend has tried playing with the idle screw but it doesn't really help. Is there anything that you guys recommend me to do to fix this?

The car drives fine to me and has no other known issues under the hood. I'd just like to get this idle fixed so I can work on cosmetics haha

Thanks!

 

I think you have a sticking throttle plate or sticking thermo wax.
If you don't mind holding the trottle a few seconds when you start the car, I'd bypass the cold assist crap. And makes pulling the UIM a LOT easier because you don't have the coolant hose to the throttle body. You ever tried putting that clamp back on that thing? I never liked the idea of a cold motor revving to 2k so I yanked that out and plugged the coolant line.
My motor idles perfectly at 900 (using the throttle screw) right at start up.
If doing this, clean out the throttle body with carb cleaner when it's off.

 

If the throttle cable or cruise control cable are not the cause then turn to the Fast Idle Cam operation located behind the throttle body.