I know this is the most common problem for fox mustang but this has everyone stumped. Car was originally a 4 cyl. and I have converted it to 5.0 efi. harness and a9l computer. The car will start then die. I can feather the throttle for about 1 min and get it to idle but soon as you blip the throttle hard or restart it will immediatly surge to point of dieing. dies at stop light/signs. I can not get this car to idle right what so ever. here are the mods Stock 95 short block flo tek heads (gt40 aluminum X equivalent) 1.90in 1.56ex 180 runner 58cc B-cam ( I know its a dinosaur cam) (cam is 4 degress advanced) Explorer lower and upper (port matched to heads) Scorpion 1.72 stud mounted rockers Professional products 70mm throttle body Under drive pulleys Granatelli CAI Stock injectors Stock mass air meter Ceramic shorty headers High flow cats/ x pipe/ magnaflow mufflers (2.5in all the way) Aluminum flywheel/driveshaft New IAC with bypass (fully open) I have done the serging idle check list and everything checked good. TPS voltage at .98 Cleaned 1o pin O2 are switching (both new) Mass air at .9 volts at idle Grounds are good. ACT and ECT voltage/ohms measure good (both new) IAC good (new) No codes Fuel pressure 38 plugged 42 unplugged (new pump) Timing set 10 degress spout out, 21 spout in (new distributor) New plugs/ wires/ coil Reset the KAM on every adjustment I have swapped PCM and mass air with known good parts off another modded non tuned fox so i'm starting to rule out electrical. The injectors and mass air come off a perfectly good car. The car will idle with the mass air unplugged or with a small vaccum line unplugged so the car i know is runing rich. the plugs are black and only have 20 miles. Can anyone point me in the right direction please.