1993 Oldsmobile 3300 engine with 118000 kms. New air filter, plugs wires and cap are good. The problem is very poor inital excelleration 0 to 40 kms then it clears up. Had the electronics scanned with no codes coming up. Mechanic suggested possible problem is the anti-knock sencor. I unpluged the sencor and check engine light came on. Motor seemed to run better but not right. Runs along ay 100 kmh with no problems. Does not miss or sputter. Any suggestions

thanks in advance

crug