mk3 golf engine idle problem

i need help my car is sending me nuts. if any one can help i would much appriciate it. the engine seems to start ok but when it warms up at idle it revs its self. some times all the way up to 5000rpm and stays there. so i had to adjust the idle screw on the auto matic idle. so now when i go to pull away and the engine is warm soon as the revs reach 1500rpm they drop to a few hundred unless you floor the accelerator. i know its not the ignition system its all been replaced and checked. i have a new air filter and also fuel filter and im prity sure its not the fuel supply. The ECU has also been tested and is fine. if any one has any ideas i would really appriciate it.

Officially, VW states that the throttle limiter (stop) screw should never be moved and if it was accidentally turned the throttle body must be replaced. With that said I have seen a method describing how to try to get it back to the proper position. You can try this; turn the screw out until there is a gap between the screw and arm, then put a piece of thin paper between them & turn it back until you feel resistance on the paper sliding. Then turn the screw 1/2 turn in. The Problem lies elsewhere, possibly a sticking linkage or vacuum leak... getting the throttle body back into proper position is the biggest problem now.