My '86 2.3L 8 valve manual trans. 120,000 miles has two problems.

1) It doesn't idle smoothly at all, you can feel the engine shaking a bit at a stop light. It's not a miss but a lumpy feel. Once above 1,000 rpm it smoothes out. It has a steady idle speed of about 750 rpm. It's never particularly hard to start but it doesn't come to life the instant you turn the key either.

2) The engine will at random times start missing when lightly accelerating or cruising, however when I step on the gas at 75% to full throttle, it smoothes out normally, and if I put it in neutral it doesn't stall. These episodes last maybe five to ten minutes then it may not happen again for a few weeks or may happen again latter that day, although the last time it happened it was raining hard.

I have replaced the plugs and air filter, and the cap, rotor and plug wires look recent, not sure about the fuel filter. Should the fuel injectors be cleaned? Is there an EGR valve to clean? Any suggestions?

If you haven't replaced the overvoltage relay, I would. It is a small part that gives alot of trouble.

If you have a leak in the exhaust manifold the oxygen sensor might cause the symptoms you mention... or a defective oxygen sensor. I had the same problem on my BMW. The tac would jump to a higher reading during the erratic misfires.

Smiles.

Overvoltage relay fuse is fine. Can I test the relay by swapping the relay from my C280 (part #000 540 67 45) to see how it runs? (2.3L has relay #201 540 32 45) It plugs right in.