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My 1990 Aerostar (the type with the larger engine) was running great, Nice and smooth, good MPG, peppy as they get. Has been well maintained. Then it needed an new alternator. Still ran fine other than the things that a dead alternators cause.
I had the alternator replaced. It has run like %$#%# since then. The check engine light comes on after 5 miles. The engine sounds OK for maybe 2 seconds and then makes sort of a lunging sound, like it is revving up and letting off. Over and over. It sounds like a engine would if a person was pressing and letting up on the gas pedal. It hesitates when I take off from a stop. It is more likely to die if I take off fast.
The car repair guy has spent hours trying to figure it out. He and his guys ran diagnostics. Found nothing other than an oxygen sensor. Had that replaced. He sounds quite frustrated. I think he has done his best. Don't think he want to ever see the thing again. Last we spoke, he suggested that I take it over to a Ford dealership to see what they can figure out. Am hesitant about that because of previous experiences with dealerships.