First of all hello... this is my first post! I apologize in advance for the long post but don't want to miss anything. My brother just bought a 94 GT 5spd. It has 100k miles and mods include: MAC cold Air, Headers, flowmaster exhaust from there back. He got a deal on it and i told him i'd help him get her in tip top shape. I guess it sat for a while and had very little gas when we got it. It was a real dog on the drive home. Some fresh 93 octane, injector cleaner and some water remover and it was a little better, maybe 50% of what she should be. Last night i removed the upper intake soaked and cleaned that, changed a vacuum line i found crumbling (from upper intake to right fender maybe the charcoal box?), changed plugs, wires, cap, rotor, cleaned the throttle body, changed the serpantine belt, and changed the inline fuel filter. All this helped quite a bit but i'd say she's at about 80%. With WOT it startes getting rough at about 3500-4000 RPM's or so. Low end she is making good power though. Can you guys give me a little info on maybe where to go from here? Thanks ALOT!!
I weak coil will show itself at higher rpm also.
I put MSD wires on mine about a month ago. The things are very tight..don't think I like it. Anyway I put a new coil on about a week earlier. So it seems to run good then I go to open it up and it is cutting out and running like crap. First thing I put the old coil back on. Didn't help. Then I'm about to put the old wires back on. Planning on going backwards with everything I did untill I find it. I find a plug wire loose, only misfiring at high rpms.
Good luck
Matt
__________________
Tremec TKO 500, Spec Stage 1 Clutch & Pressure Plate, Ford clutch cable with MM firewall adj. & quadrant, MSD Cap/Rotor & Wires, Autolite 25's, Aeromotive adjustable fuel pressure reg., SLP Loud Mouth 1 cat back, BBK CAI
FRPP C springs, Bilstein shocks and struts, M&M Caster Camber plates, Urethane rack & sway bar bushings, spring isolators.
M&M Stainless Steel braided brake hose, Hawk HPS pads, freshly turned rotors
X2 clogged cats could cause exhaust restrictions, resulting in exhaust still being in the combustion chamber after the exhaust stroke is though, and that would lead to it *choking out* the air and fire in the cylinder. anyway, also i would replace the coil to see if that would help. good luck
1994 Mustang GT Dogging On the high end 
