is this a manual? i heard about this cel with the manuals, theres 40+ pages on that on allfordmustang site. Not to scare you but theres no exact fix for this, at least yours dont go into limp mode.
13' Mustang GT, A6, Whiteline adj. phb & support brace, Roush a/b, Boss 302 brace, Pioneer door speakers, Alpine 10" 500 Watt RMS Amp and Sub, Michelin Pilot Super Sport