Timing issues. Need help

[congerz83]

Got an 86GT with Edlebrock performer II's Trickflow Street Heat upper and lower. Tremec TKO full MAC 2.5 with o/r x-pipe. I've been having this issue for a couple months now, and i've almost run out of hope. I was having an idle problem when it was brought to my attention that I had a large lower intake leak. It was repaired and the idle problem vanished. Here is the issue. I don't have any clue what type of cam is in this car. Although I know it's not stock, I don't have the specs. When my distributor went back in, my mech timed it to normal 5.0H.O. specs. I twisted the cap a little and seem to get it right. A new problem now exists. My car seems to "fart out" between 3,000-4,000rpm. Plugs should be 1yr old by now. The only thing i can think of is the timings off. How can I set proper timing if I don't know what kind of stick is in it? Please help. I'd like to cruise to bosto this weekend with t-tops down.