I have a 2001 2500 with cummins. I may be having APPS issues. It begins with a dead spot with light throttle at about 1800 rpm. The gets worse to several dead spots between 1700 and 2100 rpm, to make my normal light acceleration feel like bucking. If you accelerate rapidly, no noticeable issue. The APPS reset procedure cures, almost completely, this issue for a few months, then it comes back. What am I looking at?