Symptoms: Intermittent hesitation under acceleration. Only sometimes, and only after cold start. Would generally go away after traveling a few miles.
I was puzzled. Onset was very sudden.
Fuel pump and filter were relatively new.
Long list of possibilities came to mind, both fuel and electrical.
Then I noticed something very odd...
The hesitation happened when leaving work, but never when leaving home.
I started thinking ambient temp, and such, but that did not correlate.
On the 3rd day, I was forced to park in an alternate spot at work.
Guess what? No hesitation!
Hmmm!, I said...
Then it hit me. My normal parking space was inclined slightly 'nose down'. My alternate spot and driveway at home were inclined slightly 'nose up'. What could gravity have to do with it?
Have you guessed it?
That's right! Water in the fuel!!
The tank had been filled the day before the onset of symptoms.
Called the offending gas station about it. They were polite enough, but not exactly super concerned.
Can you imagine how many hundreds of cars in my town (very popular station) wound up with baffling problems and expensive service bills? Wonder what percentage of mechanics diagnosed the problem correctly...
Don't let it happen to you...
1986 300E 5-Speed 240k mi.