UK Car Repair: revs stuck at 2000rpm, vauxhall astra, speed block

Question
my 1995 vauxhall astra after about 10 minutes of driving wen it has warmed up the engine management light comes on and wen i stop or pull up at lights the engine starts 2 rev on its own and it doesnt go below 2000 rpm or sometimes 3000rpm just keeps going up and down on its own ty

Answer
It sounds as if the the aux air valve is faulty. Get an assistant to help do this; with the engine running at higher speed, block off the air inlet to the engine at the inlet. With no air the car should stop, probably it won't you now should be able to hear where the air is entering, it may just be a hose that has come off at the manifold!