Let me just start by saying I know a lifted jimmy is not a hot rod.. but I figured tbis would be the best place for help with a chevy 350. My engine seems to run choppy/vibratey. I'm not sure if there is a cylinder that isn't firing or if its the carb. I've had a problem when the carb would act up but we cleaned the carb. Maybe it didn't get adjussted right? It doesn't run bad.. it idles and will rev. It just has some sort of vibration I can't put my finger on