Have a Chev silverado 1500hd 6.0 liter 4 x 4 crew cab. Love the truck but need to pull trailer.
Problem: My eng idle is good. If i rev it sounds great. Drives normal but a bit sluggish,however when i put my foot into it...it has no acceration or power...eventually it will kick in like it wakes up. I also notice hard shifts so its something that affects the powertrain. Any thoughts what could be wrong? So far i have fixed the intake gaskets, replaced maf and replaced both o2 sensors before the cats.Maybe next thing to look at is an exhaust restriction. Any ideas would help.

 

Does it have any codes it's throwin? How many miles are on it?

 

Truck has 120000 miles. Yes it had two codes PO101 and PO145 showing up on the scan.

 

Sounds like your MAF and O2 sensors are having fits. I experienced the same problem with my truck about a year ago. My fix was simple; I took out the MAF, cleaned it and blew it out with compressed air and had the codes erased. To this day, they haven't returned, and my acceleration problem was fixed.

Disclaimer: 1:The PO145 code didn't pop up; only the PO101. 2: If you break your MAF, I take no responsibility. You're on your own if that happens <3