Arthur,

I did as you suggested and re-set the EA and the HFM. After driving for a few days I checked for fault codes. There were no faults on the Pin 14 EA. The HFM on Pin 8 returned one code: #9 O2S 1 - Voltage too high, circuit open or voltage implausible. I think I have only one O2 sensor one my car. Do you think this O2 Sensor could be bad?

If so, I've read on some posts that generic O2 sensors or O2 sensors from late-model Mustangs work the same as the OEM but are much cheaper. Any idea if these other units would work on my '93 300E 2.8L?

Thanks again for the replies,

John B