Sticking revs

[andykram]

What do you guys think this might be as I'm a bit stuck. Car is a run out 92 8v GTi
When it's warm (it doesn't do this when it's cold) the revs will stick at about 1500 when you disengage the clutch e.g. on coming to a halt at a set of lights. If I blip the throttle it mostly (but not always) settle back down to normal 1100 ish. It then idles fine and in all other respects runs fine so I can easily live with it but I'd still like to solve it. And it won't stick every time I disengage the clutch, just sometimes.
I have removed the ISV and cleaned that with carb cleaner. Could it be a sticking throttle cable perhaps? Why does it only do it when its warm? All very curious.

[theclash]

check throttle cable aint to tight,check all vac pipes for leakes,check wiring to micro switches on t/b, have a read of rub johnnys tune up guide will give you some pointers

[dadrathers]

My money would be on the idle micro switch on the throttle body. The little tinker is hidden under the throttle body but can be checked easily. Either open the throttle manually and listen for a click just as the throttle closes or connect a multimeter to the supply to the micro switches and check for open circuit/closed circuit as you release the throttle.

To adjust it you will have to remove the air hose from the air box to the throttle body to gain access. Luckily all can be set up without the engine running.