Ive got a 89 mustang I recently turboed. Has everything needed from the qft 650 blow thru to the a1000 fuel pump etc. Ive recently had a prob with the car not wanting to rev past 4500. It starts what feels like cutting spark around 3k but like a full cut at 4500. Idles smooth and all. A/F ratios are not rich around 13 when this happens. Ive replaced to plugs and gapped them to 25 and even replaced the coil and distributor and still same prob. Car ran great for a day or so once finally got it all dialed in then went to fire up next day and this happens. Im stumped here. Checked resistance on plug wires and they check out. Not sure if the btm boxes are know to go bad or what. Hell its only 2 months old bought brand new.