i have a 94 gt and if i take off hard, when i get to 4500 rpm it sputters when it is in gear but when it is just reving it will go all the way to about 6500 rpm.
what could it be???

 

run a koeo/koer test ..check for codes..if none.. check secondary ignition components such as car, rotor, wires and plugs

 

TFI module maybe ???

 

Partially clogged fuel filter causing it to lean out under a load @WOT?
Like mentioned, a good tune up wouldn't hurt. Plugs, wires, cap, rotor and fuel and air filters.

What cam is in it? Stock? Weak valve springs perhaps.

 

+1 on the tune up....9 times out of 10 thats your issue with a relatively stock set up....I had the same issue on two of my cars when I bought em....tune up did the trick....you dont want to rev higher than 5100 anywayz...valves probably floating all over the place....ha