While driving on the highway can’t get above 3000 rpm or when it will it only momentarily does surge and give the engine the ability to accelerate above 65-70 mph. (Highway speed is 80 mph.)
The engine computer is programmed to limit the RPM to 3,000 when not in gear by cutting off the fuel momentarily. I suspect that the computer is faulty or it’s not getting a signal that the transmission is in gear. With the transmission in PARK accelerate the engine to see if it will begin to surge at about 3,000 RPM and if so compare the surging to what occurs when driving.
You might also consider a problem with the TFI ignition module. Check DTCs and see if there is anything related to loss of a PIP or SPOUT signal.
It could be that the ignition timing is not advancing and remaining retarded.
1989? Is this beast carbureted?
our 88 f150 was injected. 302/5spd. took forever to sell. none likes clutches on trucks in the big city.
Tried this one and didn’t have any issues getting the RPM up into the red zone.
Engine air filter, fuel filter, fuel pump, or cat are things to consider.
Finally got around to changing the fuel filter and that seems to have solved the problem.
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Thanks for the update. You’re lucky you didn’t trash the fuel pump in the meantime (like I did on an '86 Ford Tempo).
Good for you for getting it solved. Best of luck.