My Opel Kadett 1990 - 1,6 (200 000km) came back from the mechanic a few weeks ago - where he had replaced the automatic choke. But now the problem appears again. Whenever I clutch it sounds like the accelerator is beeing pushed to the bottom eventhough I'm not touching it. When driving in a low gear 1 or 2 it behaves like an automatic car even if i is a shift-stick - and it keeps on driving whithout me touching the accelerator. When I set it in Free gear - it behaves like normal again - what is wrong??