I know that this seems like a silly one, check the harmonic balancer to see if it has spun on the rubber ring inside it. A car I worked on gave the same symptoms, turned out that the balancer spun and was firing the crank sensor at the wrong time worth looking at at least
A Friend brought me his early '90s olds regency with the 3800. It seemed to have a decent miss at idle which was tracked to the #1 injector. When I unplugged the injector(engine running) it didn't change the idle. Also, when going down the road, the car would shutter fairly severe under light to light/med acceleration. When you give it med and up throttle, it would take off smooth as silk, and fairly powerfully too.
I replaced the injectors...Idles great. Took it for a test drive and was awesome under all throttle. Gave the car back and it started doing the shutter again after a long drive. A mechanic Friend of mine thought it might be a trans shutter and did a filter and flush. It didn't help!
Possibly-
Plug wire?
Injector plug/harness?
Trans pressure?
Coil?
Coil plate?
??? ??? ????
Any and all ideas would be GREATLY appriciated!
Injector harness, Mass airflow sensor or Crank position sensor
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