I have a 2004 Colorado with the 3.5. I use this truck to deliver mail out of. It’s been a great truck. But it has started stuttering and wanting to go dead when I take off slowly. If I take off fast it does fine. Also idles great and runs great at hwy speed. It’s just when I slowly accelerate and also only does it after running for 4 hours or so. Once it cools off you can get it in and drive for 2 hours with zero issues. No check engine lights and I’ve already cleaned the throttle body and put a new fuel filter on it. Any ideas?