i had the same problem with my 89 190e i replaced the crank positioning sensor and the coil and now it drives great .... if your car is befor the obd2 then you can put a GM coil in there and it will work plus you will save hundreds if you go that route ..... and the GM coil gives it more power so it runs better.... and the crank sensor.... go to a junk yard and find one thats clean inside.... trust me you'll save a lot of money that way