So my '97 K2500 with 6.5 TD is starting to act up. The truck has just about 200,000mi on it. I bought it fairly young with only 13,000mi on it, the injection pump and PMD were replaced under warranty at about 45,000mi. It is manual transmission equipped. It's acting really weird now. It surges, like a power boost, then backs off quick, causing a buck. But it doesn't cut out. When the PMD went before, it was a defined cut-out. I've replaced my fuel filter quite regularly at around 10k intervals, the lift pump has gone out twice, I know what that feels like - The truck still runs and drives, but if you get on it, it cuts out. It's not that. This is new. The power boost surge then a quick back off. my truck is a manual transmission, so the back-off causes a buck and driveline shock. I suspect in an auto tranny, the torque converter would soak it up and you wouldn't feel the buck. '97 was the first year for drive by wire accelerator too. It has always had a problem with cruise control, trailers and hills. If I was using cruise control, with a trailer, if I get into hilly areas and forget to turn the cruise off, it will kick and buck going down hills, like GM didn't do enough testing with the drive by wire on the manual trans. It has always done that since new. That feeling is what it feels like now, only it's unloaded on flat roads. Oh and, it only does it when it's cold. It's not cold outside now, in the 50's and 60's, it mostly acts up just for the first 10-15 minutes while the engine warms up, then the problem subsides. I can still kinda a feel a surge when it's warm, but nothing like when it's cold. Any ideas where to start to diagnose this one? Drive by wire system? Injection pump? It's not popping any codes, I've a buddy with a tech 2, no codes. I can still drive the truck, but experience tels me, problems like this don't fix themselves and will most likely get worse pretty quickly. Thanks for any insight.