I have a 2001 f-150 with the 4.2 ltr v.6. At about 60 to 75 mph the truck seems to lose power for just a split second but repeatedly. It doesnt always act up either tho. Its like the fuel supply is hiccuping and the engine gets gas on and off for just a few seconds. I have changed the plugs, wires, coil pack, cam shaft sensor and fuel and air filter. nothing seems to help it. Could this be the intake manifold gasket of a head gasket leak?

 

seems like you headed down the right path to correct it.

Have you had the codes scanned? Have had the fuel pressure tested?

what kind of "coil pac" was installed?? Can't say that the V6's coil pacs are as trouble some as the V8 COPs ( coil on plug)...but the COPs can be bad out of the box.

I have a co-worker that has nearly the same truck and he sunk $$mucho denaro$$ in his before it finally was his straightened out. They last suspected that the cam shaft sensor was improperly installed...like 180 deg off on engine timing or faulty??? IDK for sure. but he ended up with a whole rebuilt top end of the engine...heads and intake manifold were off twice if memory serves and to 3 different shops. Not saying that what is wrong with yours...just a example. Shucks it might be a simple vacuum leak.

I would go some where they have a scanner that is mode 6 capable...in other words able to see/watch each sensor function and able to graph it or record it.

 

What brand ignition parts did you use? Have you tried a bottle of Techron in the gas? You may have dirty injectors. Have you ever cleaned the MAF sensor and throttle body?