98 gt losing power.

ok, i have a 98 gt with O/R H and flowmaster catback, and 3.90's. my friend has a 94 GT with O/R H and MAC mufflers and underdrive pullies. we raced a few days ago and i got him from a stop and a roll by about 2 cars. we raced again tonight and he actually pulled me from a 3rd gear roll and i cant pull him from a stop. i also used to be able to bark 3rd gear, it will not do it now and hardly spins 2nd. and i got on it around a corner in 2nd and it wouldnt even break the tires loose. the car doesent run ruff or anything its just lost power somewhere. i just changed the plugs and the plug wires are newer. i also changed the IAC and PCV and air filter recently. the problem didnt arise until after i got gas today (BP 89 octane) i usually use 93. anyone know what it could be? my car has 73k miles on it. my brother said my coil packs might be going out. every so often it hesitates and misfires at low rpm. if you guys think its the coil packs, how much do those run and what are the good ones? thanks for the help in advance.

nate

i think it may just be my fuel filter. i hope it is anyways. it often misses when i get off the gas and get back on it. i have a filter so ill change it and if that doesent help i guess ill have to look elsewhere for the problem. on a side note i raced a friend of mine that has my old 95 Z28 6-speed. its got an intake and magnaflow catback. and he could bearly get a car on me. so i was happy about that.

im going to do that tomorrow. i really dont want to spend a bunch of money as im saving for the PI intake kit.

pretty sure. i gapped them to .054. im going to check the plugs tomorrow too just to see how they look.