check out the 2e2 repair guide in the mk2 maintenenace section. running on can be casued by carbon buildup in the combustion chamber, which is in turn can be caused if the car is running rich. the rev to 2k thing can be caused by the waxstat not getting a good supply of coolant due to a blocked coolant chanel o'ring in the inlet manifold. this coolant feed also supplies the autochoke, which will make the car run richer than it should do. another cause of high reving can be the 3/4 point unit