I have a 1988 300E, with 100K miles. The car starts fine and is fine at highway speeds but has a very rough idle, the RPMs range from about 5-800, and the needle fluxuates slightly. The vehicle shakes as well at idle. When I step on the gas pedal, there is a lack of reponsiveness. Usually, I will step on the gas and it acts like it will stall and then the engine catches up to the gas pedal and accelerates as it normally would. It stalled once at a stop sign. Any ideas on what may be wrong? Thank you.

 

are u shure its running on all cylinders while running pull spark plug wires off plugs one at a time and if you come to one that dosent make it idle any different that cyl could have bad plug bad wire you should see a big change each time you pull a wire