Ok I've tried searching and I can't seem to find anyone with the same problem. When I am driving at a constant speed, around 35-40mph and between 1300-1900 rpm, I notice a surging or hesitation feeling. I've read that it could be the UVC, IPR and the CPS (hasn't had the recall done yet). Well I'm pretty broke so I was hoping to get a little more diagnostic advice before I start swapping parts. I don't have access to a scan tool for free and I'm worried that if I keep driving it I'll make it worse. This just started happening this evening. The truck was warm as well. It only seems to happen when it's not underload or I'm not accelerating. My mods are a hypertech (old school) 50hp chip, MBRP 4" turbo back and the DIY Tymar with the 6637. I'm pushing 188k on mileage. Any ideas? Could the ICP plug cause this?