I just bought an 88 gt and have a big issue. I just did a Mass air conversion but the problem was happening before then. when cold the car runs like ****, will not idle or accelerate and will pop and backfire till the car gets warm and then will run fine. so far i have put in 2 new o2's, ect, idle air motor, new computer, mass air flow sensor, fuel filter, adjusted the timing and nothing seems to be working. it runs rich as hell u can smell it upon start up. HELP????????

 

have you checked fuel pressure?

 

If fuel pressure checks out you try testing the tfi module... If you end up getting a new one make sure to get the right one for what tranny you have

 

yeah i have a brand new msd tfi on it. also fuel pressure is okay. wondering if i have a vacuum leak on the intake.

 

I've had the same problem with mine since I got it about a year ago. Same thing won't idle when cold, pops and runs rich as hell. I noticed that the previous owner broke a whole crap load of vacuum lines and attempted to repair them by putting a piece of rubber between the gaps. After replacing all of them with silicone tubing it has yet to stall out when it's cold. It does seem to reach idle before I think it should when it's cold, but it doesn't stall. I can drive it long before it warms up. I'd start replacing all the vacuum lines. It's cheap and 9 times out of 10 it'll fix the problem. The only difference between our cars is mines an 87 and still speed density.