replace the whole distributor. I know you put in a new pip and TFI but you still have a bad dizzy. I had a car do that exact same thing, dizzy fixed it.
heh, i'm a founding member!
if it's an 86 lincoln MK 7, it's the same as an 86 mustang GT.
flat top pistons, 58mm throttle body, E6 heads, speed density.
the 89 mustang, of course, would have pistons with valve reliefs, 60mm throttle body, E7 heads, and mass air.
first and foremost, check the fluid. make sure it's clean, and full.
secondly, the OD band is the weakest link in the AOD tranny. it's done for.
are you sure it's only slipping in 3rd?
how "good" is the spark? if it's faint, it's probably in the distributor. my car did that same thing "won't start when warm" and it was the pip sensor in the dizzy.
don't mess with the body, most people that do aero swaps (or even just put ground effects on) just do a half assed job of it and the car looks like crap. fix up anything on it that needs repair, but keep the outside of it essentially stock.
you'll need the fuel lines, and the brake lines...