the car warms up and misses under a load, going up a hill, A/C on, accelleration. seems to run well cold, but quickly goes downhill. in hot weather it's hard starting as if vapor locked.

thanks for your response.

I believe that to be the M104 engine, vacuum leaks are common under the front plastic cover for example, but your symptoms sound much like a bad ignition coil (original blue-tag Bosch were notorious) which can fail at higher temps (or sometimes at all temps). Check the "plug connectors" between the coils and spark-plugs beneath them and spark-plug wires, also a common failure which could produce your symptoms. Also, are your plugs platinums? I have read here that the platinum plugs are not a good choice for the M104's waste-spark system, I'm happy with NGK coppers in all of my M104s.

Any engine codes?

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Gone to the dark side

- Jeff

It is an M104 HFM engine. Build a code reader and pull codes.....

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1993 300E, 2.8 M104 .....