1994 gmc k 1500

[drs-machine]

Hi there my truck from 0-60 is fine when i take off. When im cruising and i start to reach the 40-45 mph the truck loses power and the pedal has no response until i hit the pedal at least half way and then it kicks out. This always happens at about 40-45 mph. The truck has 137k and has had a tune up wires, plugs, cap, rotor, coil, new distributer and new fuel pump/assembly. Any ideas would be appriciated since my so called mechanic cant even figure it out. Sorry should have said earlier that is has 5.7 350 but sure you knew that already. Thanks

[Wingnut]

Have you given the throttle body a good cleaning, inside and out?

[drs-machine]

I had this problem with the stock tbi. I upgraded to the holley 670 cfm tbi with same prob.