Tune up

[Mr. Jimmy]

My 89 Jimmy w/350 TBI has started skipping or surging around 2100 RPM in Drive, problem doesn't seem to exist anywhere else such as running in OD, doesn't seem to be as noticeable when engine hasn't been completely warmed up. I have replaced plugs, rotor, cap plugwires and fuel filter. Any suggestions?

 

[Z3PR]

It's so hard to tell on a computer controled vechile. If you don't have a scanner, take it in to a shop and let them figure it out. Once you know for sure what is cousing it to surge, then you can fix the problem.

 

[Thunder]

Have you checked for trouble codes?
Click here if you dont know how:GM trouble codes.
The way you describe the problem sounds like, in my best guess. A bad magnetic pickup coil or the Distributor module may be going bad. If so you will probabally get a code 42. Both units are located in the distributor.
If you are going to work on your FId truck.I highly recomend getting a scanner. Using a scanner is the best way to diagnose problems with TBI. You can get a Auto X ray scanner at most autoparts stores for around 150.oo. they work good. They have a 30 second capture mode that you can activate when the problem occures. It will store all the info fron the sensors and engine operating data. It will really help with driveability problems at a certian RPM.
Dont but a cheap 25.00 one. All they do is turn on the check engine light. You can do the same thing they do with a paperclip.