I have a 1993 MB400E That runs great until the heat gage gets to 80+. Then the engine will miss intermittently when you accelerate. Sometimes it stalls and won't start until it cools for awhile. I've tried to fix by replacing plugs, ignition wiring, injector wiring harness, oxygen sensor, fuel filter and pumps, fuel pump relay, coolant sensor, 2-pin and 4-pin coolant sensors, air injector relay. All vacuum lines were checked also.

For a DIY I've done all I can think of except go to an expert who knows what he's doing. Does anyone happen to know my problem or problems?
Thank you.