'93 GMC Jimmy 4.3L Vin 'W' Running issue

[mr_stimey]

As a followup to a problem I had about 3 or 4 weeks ago and resolved in this thread, I am now back to troubleshooting an odd running issue.

Problem: Will start and run fine. Once engine comes close to temp ~195, or after just about 1 mile of driving it begins to miss and lose power in the throttle no matter what speed/gear. It will still run long enough to get it parked and eventually die out if you dont turn the key off.

No SES codes are thrown whatsoever. No rich fuel odors to signal a leak or unburned gas. Fuel pressure checks out at startup and idle, if Im losing pressure while driving I dont know how I would check that.

Recent work done: I replaced MAP sensor to resolve an issue in the thread I linked above, plug wires, and also replaced fuel tank, sending unit and pump (Delphi) a couple weeks ago.

Without any codes I am at a loss of where to start, since it appears the ignition and fuel systems check out. Any input would be great.

Cheers,

Tony

[old_master]

Key on, engine off, fuel pump running, fuel pressure must be 60psi to 66psi. Fuel pressure must remain above 55psi for 3 to 5 minutes after fuel pump shuts off. GM does not publish any engine running fuel pressure specs, all checks are done with the engine off. Post your results.