I have an 02 Gt, with a stock top swap and headers running 91. I've driven it for almost 40,000 miles with this setup and had no problems, other than when i first finished, the coils needed to be grounded better. Just recently it has started to randomly misfire. When i checked, it hadn't thrown any codes for it. It seems to happen under load, like if i get on it a little more when i accelerate, and when im cruising 65-70. It will be cruising fine and then it will randomly misfire/start to break up. I know the tune that's on it is a little rich. Should i put new plugs in? What other things should i do?
