My 01 Lightning is surging real bad but only at wide open throttle. Runs fine as soon as you let the pedal off the floor (which sucks). Just completed a tune up. Truck has 4lb crank pully, COI, exhaust and diablo program.
PLEASE HELP!!!!!!!!
THANKS

 

What do you mean by "tune-up"? These trucks don't need tune-ups (the computer self-adjusts). What exactly was tuned up?

 

Sounds LEAN to me, my 04 was doing the same thing. By any chance do you have a air/oil separator ? Or maybe your PCV is sticking open at WOT. I removed the air /oil separator,(and the PCV) plugged the intake, then I ran a 3/4" heater hose onto a -10 AN fitting and stuck it in the valve cover. (it vents to the fender) Easy to return to stock, AND....it worked !

 

Sounds like belt slip. Check for black reside under S/C pulley.

 

All engines that use spark plugs need tune ups. Changing the ignition components for maintenance is a tune up. I'm curious to know which components were a part of this tune up.