if you get on the throttle between 2.5k-4k rpm, car runs rough and if you keep on it, she will misfire cyl 4 at minimum. If you stay about 4k rpm you can go full throttle until you let the rpms go below 4k then you have to slowly throttle up to 4k RPM again before you can get on the throttle. Stage0 just made it to where I have to give her a little more throttle during low RPM to fail. So it seems at about the same power level between stage 0 and stage 1+ there is failures. but also ran great at low rpm before getting E85. Only thing changing between not running well, running great to E85 failure was I changed spark plug on #4 and found, 5,3,2 were loose, i tightened. car ran great. got e85, ran like shit, flashed e40, ran like shit, flashed back to stage 1+, car still runs like shit, flashed back to stock, car runs like shit again