Was wondering if anybody has experienced this same problem I swapped my 4.3 out for a lq9 an when it was finished I took it easy for the first week an when I finally did open it up it shot up to 6krpms but didnt move from a 60 punch it will do this at any speed below 70 but it will fly if I do a 70 punch no mods have been done to the stock 4l60e could it be the engine is too much for the tranny? Or could it be the tune? Any advice would be greatly appreciated as this is an annoying problem because nobody ever wants to do a 70punch lol