Hi. I've got 87 944 NA. I'm Live

I have this kind of problem. First when the car is cold in the morning it starts and idle low and unstable for 2 secs and then stabilizes. Later when it's hot Idling is about 1200rpm. Waht i it? I have second TPS checked and it's still idling high.
Could reference sensor do that? - the problem started to occur after reinstalling those sensors.

But it's only idling high after driving, when hot. The low idle at start is a new thing too.

 

Have you cleaned the throttle body. The butterfly gets totally coated with crap and it can prevent the valve from closing. I had rough idle and just lived with it until I decided to clean up the intake and it makes a big difference.

 

It sounds like the control sending unit located underneath the intake manifold. I had the same problem on my car and I replaced it and that one was faulty also. They way you will know if it is bad is by letting it go and if your car tends to surge between 1000 to3500 rpm than it is bad to stop that i tapped it with the handle of a screw driver or my ice scraper.