Not only am I new to the site, I just bought my first diesel. It drove out good when I tested but made a 60 mile trip yesterday and have some real concerns. (2006 Ram 3500 mega 5.9L turbo). When I let off the accelerator it seems to "pop" or "grab". Sounds like it is coming from the rear of the engine compartment next to the firewall. (6 speed standard). When using cruise control it does great going up hill with none of the typical gasoline surge, however, when going downhill it starts to jump or "buck" and acts like a gasoline engine that needs a lower gear. When I step on the accelerator and add a little power it quits doing this. Only an isssue when going down hill or coasting. Any help appreciated as I am considering putting the sale sign back on it.