Truck Sputters Under Acceleration.

[91jimmy]

Okay guys here is my problem

My 1991 GMC Jimmy would sputter under acceleration once it gets up to speed (35-65 mph) it would be fine, but if I would try to pass it would sputter again then go back to normal. Now I know what your thinking ignition problem right well I thought the same. Here is a list of things that I have tested or replaced, and the problem still remains.

• Ignition wires = replaced
• Cap and rotor = replaced
• Timing checked and dead on.
• Plugs checked looked good no presents of misfire, but replaced anyway.
• Ignition coil= replaced
• Pickup in distributor was tested as described in the manual, and tested to be good. Truck retimed as described in manual.
• Ignition module replaced about a year ago.
• Truck had an uneven idle, so I replaced the Idle Air Control Valve truck now has a smooth idle.
• Vacuum lines check and replaced.
• Fuel filter = replaced
• Fuel pump was replaced about three months ago.
• PVC= replaced.
• Muffler was replaced I also had the CAT and O2 sensor replaced since I barely passed my smog test last year. The guy who tested said they were due.

The only thing I recently did to the truck before this started happening was replace the transmission fluid (Royal Purple). The transmission had 65000 miles since its last change. Could this be the cause of my problem the new fluid freed some debris and clogged something? While I did manage to fix two things my idle and my driver side window works now.

Any help would be appreciated.

Thanx

Mike

 

[Thunder]

Have you checked for trouble codes? Do you have access to a scanner or Win aldl?. It wouod really help to know if your sensors are operating right and what they are telling the ECM.
Wthout a scanner that gives you realtime datayou can only guess.
How is your EGR valve? you could try pulling it off and cleaning it. It could be stuck open
The Throttle Position Sensor may be bad.
The map sensor could be bad.