so ive been looking for the problem for some time now... my cars a 90gt supercharged 80mm mass air, 70mm throttle body, 42# injectors, cobra upper and lower, gt40 heads, b303 cam, 255 fuel pump, msd 6al box, motorcraft dizzy and wires, new plugs. Ive had a stumble for about 2 months now to the point i couldnt even drive it... its cleared up since i cleaned my mass air and filter and did IAC, TPS, EGR, and fuel filter however its STILL hesitation/missing/stumbling at like 1700-1800 rpm... What could be causing this now? My car currently is overheating so i did a new radiatior but i believe the thermostat is sticking... i dont think that would cause it to be missing but i dont know... im still a kid and this is my 1st mustang. But i need this problem fixed so i can atleast enjoy my car... Does anybody know what i should do?
p.s.- should i get a 180* thermostat or stay with the stock one?
Pull the radiator cap when it is COLD. Run the engine untill it warms up and opens the thermostat. Look for air bubbles in the radiator while it is running. If you have bubbles you could have popped a head gasket. If the head gasket is leaking it could cause a missfire. Antifreeze on the spark plugs will not fire. Pull the dipstick and see if water is in the oil.
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337 C.I.D.
390 R.W.H.P.
362 R.W.T.Q
11.44@120 in the 1/4
7.35@ 95 in the 1/8
1.60-60'
N.A.
1988 L.X. Hatch 5.0L 5-Speed, 85,000 original miles
It could be your temperature sensor is bad . It could also be your o2 sensors going bad too. But I think RETRO 5.0 has the right Idea that it probably is a head gasket . Try pulling all the plugs and keep them grouped with the cylinders you take them from and see how they are burning . If you find a real clean plug and the rest are carboned . Then the clean plug is your bad cylinder .