04-22-2014, 04:05 AM
Just throwing this out due to the symptom description...is it possible it could be the TPS without registering a code? I had a similar situation in my 1990 driving at highway speeds. It felt like someone was either nudging the bumper from behind or hitting a 60 mph head wind for a slit second. It was very sporadic in the beginning. Turned out to be a bad TPS.