starts and runs fine but under slow acceleration at any speed it runs ruff untill I hard accelerate past it. the problem occures about the 2000 RPM range. I have replaced plugs and wires, mas air flo, throttle position, coils and modual. I cleaned all injectors and ran 3 tanks of preamum fuel with napas best injection cleaner an 1 with sea foam, still have the same problem. I had a shop run a test and it shows 2-4-6 injectors as miss fire but still firing and torque converter stressed, probably from when we did a vacuum leak test. shop told me to take it to a dealer because his test was generac and the dealer would have better information and that it might be an intake manifold problem. There isn't any water in the oil and no oil in the antifreeze and no white smoke out the exhaust. I'm stumped....