I recently acquired my first F150 4x4 supercab with the 5.8. Its a 1992 and has 120k and is in great physical shape. My problem is when going down the open road at enough throttle to maintain my speed, you can feel a slight studder or a miss. Truck idles fine with just a little miss every now and then. When cold or WOT it runs fantastic.

What I have replaced: Spark plugs, wires, cap, rotor, air filter, crankcase breather filter, pcv, new IAC, new TPS calibrated to 1.0 volt, cleaned EGR and tried another MAP sensor for fun.

Could this be a fuel pressure issue or problem? Truck runs great when you are accelerating.

What should I check or test next? Any help or thoughts would be greatly appreciated!

Maybe O2 sensor? If it runs great when cold and at WOT (when the PCM is in closed loop), it would lead me towards this.

Probably about time to replace anyway, if it hasn't already been done.

Have you replaced the throttle position sensor. Mine went and that was also happening to me.

Did any of these ideas help? I also have a 1992 F150 2wd 5.8L that does the same thing. I could use the help if any of these ideas helped you...

Monty