Hey Guys,
I just bought a 1998 K1500 5.0 Vortec the truck starts and sounds fine until the truck is about to shift gears. The truck starts to hesitate at Higher rpms if you let off the throttle and let it shift and give 1/4 throttle it runs ok. If you floor the gas, once it goes past about 3-4k rpms the power is gone the motors screaming but not going any where. Check engine light is on and was reading miss fire and egr valve. I changed distributor cap, rotor, plugs, wires and egr valve after all that the truck still is hesitating at higher rpms. Engine light went away till I went on the high way and the truck was working hard to get to 65 and the light came on. Can this be a mass air flow sensor or throttle position sensor? Can someone steer me in the right direction this truck mechanically seems fine I know it has to be some type of sensor or maybe clogged cat? Please help thanks

 

Hey, I am having the same problem with me 98 GMC Sierra 5.0 vortec. Just wondering if you ever got it fixed, if you did what was the problem? Lemme know when you can, thank you.

 

The cat converter was clogged. It ran like a top once I installed a New one.

 

Awesome! Thank you for your help!