I need some help, I tried searching first but didnt find anything. My 87 Gt has been misfiring for a while now but its only getting worse. I had a fresh tune up about a month ago thinking that would fix the problem but it didnt. The car misfires at all different times, sometimes on quick revs or if I try to launch it will give a huge pop from under the hood and it feels like it loses all power and then all of sudden picks up and goes and there was another time when I was just cruising in 4th and tried to floor it and BOOM. The timing is good I know that and it has fresh plugs,wires,rotor & cap,fuel filter and pcv valve. I asked my mechanic what he thought and he told me its gonna be a tough fix because it doesnt do it all the time, I think hes just lazy and doesnt wanna look. Im really starting to get fraustrated because I wanted to run the car soon but I cant cause of stupid crap like this. Can somebody give me like a checklist of some other things I can check to get rid of this problem or atleast locate it. I appreciate any help you guys can give, Thanks.