Famous 2000 Gmc Yukon Check Engine Light Flashing Ideas. Engine runs rough, hesitates, or jerks when accelerating; So my check engine light came on flashing about a week ago then went away, but it started flashing again to day and went off for about 5min then came back flashing on and off then went off again and never came back on, have any idea what it is?

Engine runs rough, hesitates, or jerks when accelerating; It also shakes and has a smell when i drive up hills. It only happens when i do the works wash.
