Ok, I just replaced the oil pump on my 89 sidekick, and now it drives ok, but at 4k rpm, the engine cuts out like i hit the revlimiter.

Not really sure where to begin troubleshooting this, thnaks guys
Ken

My guess is the oil pump is not related to the problem.  How is your fuel filter?

no clue, I'll try that, but its a distinct cutout, in any gear, or even in neutral.  revs up to 4k fine, then the engine cuts and drops back down.  The trucklet sat for a week and a half while I did the oilpump/installed diggers spacers/cleaned radiator/replaced fan clutch.  Non of which should cause this.  could it be the timing belt off a tooth?

any other ideas?

found the issue, the timing belt was off by one notch.  must have misaligned my match marks when I reassembled it.  Got it half way back together after adjusting the belt, but only had 30 minutes to work on it today before I go to work.   

How well did it pull before it cut out?

very weakly, I could drive it, but not well.  then it would cut out like the ignition was interupted, and when the rpm came back down it would run better.  But it didn't set off any check engine lights

OK, I was thinking it should have pulled stronger but I guess the ignition timing was out too

was it one tooth  advanced or retarded?? zaggy was telling praire and myself. one tooth advance would kinda wake her up a bit...

Not without re-setting the timing,
get these little engines retarded in
the timing and they run slugish, just
a few degrees makes a big difference

it was retarded one tooth, just like me for putting it back together off

Had you re-set the ignition timing
it would have run fine, in fact a little
stronger on the top end RPM, but the
timing was retarder with the cam, and
made it a dog

Sorry you had to do all that extra work
for a timing problem

its not that bad, I don't have any extras like power steering or AC, so it only took an hour and a half or so to figure out the problem and fix it.  That and air tools help.