So my 2000 GT runs great except but after it warms it will hesitate (with a rumble like feel) sometimes when cruising around 30 mph. When I apply more pedal it clears and accelerates find???? If I cruise above 40 no problam.
might be slight missfires due to the need to change plugs or a new coil pack. when was the last time the plugs were changed/how many miles are on the car?
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Procharged 2002 Mustang GT 5 Speed 351rwhp 353rwtq at 10psi
Next summer looking to go with:
Bilstien shocks + struts, Lowering springs (brand still TBD (any suggestions?)), MM CC plates, front + rear sway bars, subframes, and upper and lower control arms.
Time to make the pony ride some rails
OK...Stay with me 193K ...LOL see my high mileage post.
I put new plugs in it and have changed the fuel filter. I've focused on fixing some issues to pass inspection and all that is complete. I don't have a CEL.
it is very likely that one or more of the cops (coil on plugs) have gone bad with that many miles. a ford dealer can test them for you (for $90) and then sell you each individual cop for $112. or you can buy a whole set of 8 from summit (that's what i did) for around $250.
some people swear by the oem coil packs (motorcraft). you can get them online somewhere for like $40 each. i think late model restoration has them but dont hold me to that. im sure someone will chime in.
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Procharged 2002 Mustang GT 5 Speed 351rwhp 353rwtq at 10psi
Next summer looking to go with:
Bilstien shocks + struts, Lowering springs (brand still TBD (any suggestions?)), MM CC plates, front + rear sway bars, subframes, and upper and lower control arms.
Time to make the pony ride some rails
No codes yet...I'm thinking someone else has experienced this condition and I'm just looking for the possible cause. It almost feels like it's a trottle or gear shift problem. When it happens it feels like your on a rumble strip in the road. It will clear if I increase the trottle or decrease the trottle. This car has 193K miles and I haven't tried preventitive items like trottle body cleaning, injector cleaning, etc (have replaced the plugs, fuel filter, air filter).
it doesn't always throw a code when a cop is bad. i was having severe misfires when my tuner was trying to dyno my car with the supercharger. a couple of the cops were bad and the sparks were getting blown out, no code thrown.
but you said it feels like a rumble? my misfires felt more like lurches or like you were going over non-consistent bumps in the road.
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Procharged 2002 Mustang GT 5 Speed 351rwhp 353rwtq at 10psi
Next summer looking to go with:
Bilstien shocks + struts, Lowering springs (brand still TBD (any suggestions?)), MM CC plates, front + rear sway bars, subframes, and upper and lower control arms.
Time to make the pony ride some rails
unfortunately you need a special tool to check the cops and see which ones are bad or not (and only ford has it). my tuner just told me how many misfires i had, didnt tell me the cylinder. i just ordered a whole set of cops because the price was right and i didnt want to pay ford $90 to check my cops
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Procharged 2002 Mustang GT 5 Speed 351rwhp 353rwtq at 10psi
Next summer looking to go with:
Bilstien shocks + struts, Lowering springs (brand still TBD (any suggestions?)), MM CC plates, front + rear sway bars, subframes, and upper and lower control arms.
Time to make the pony ride some rails
2000 Mustang GT, Hesitation after Warm 
is bad
