If the timing belt has skipped a tooth, it can run well intermittently and accelerating power would be greatly reduced.
Anyway I am not referring to skipped tooth, just that if the tension of the belts is loose, it can cause the timing to be erratic.
Is the CEL still coming ON?
A clogged catalytic converter would result in unability to accelerate more than 3000 rpm most of the time.
A misfiring cylinder would cause the catalytic converter to run red hot.
You can try disconneceting the cat converter to test of it is plugged.
Thursday, January 10th, 2019 AT 2:59 PM
(Merged)