massive run rich problem-HELLLPPPP

[rodster]

Hi all, Here's the history and the problem.
89 supra, red, targa, gte.
rebuilt motor about 7k miles and 4 years ago.
Uncle drove it and the tentioner loosened...
jumped teeth=bent valves. He bought a 97 tt and gave
this one to me. I have been the sole mechanic since we bought it in 92.
sat 3 years in back yard while i collected parts, rebuilt head, ect.
inside had a leak during this time and fungus galore.

ok, i got it all back together. started it up, idle problems.
iac motor sludged. iac cleaned. it idles beautifiul.
drive it. doesn't develop full power and misses above 4-5k.
drivable, but not what it should be.

Anywheres between 10 min to an hour, all of a sudden give it gas and
it immediately stumbles, falls flat, black smoke out the back, and the
chek engine light comes on. from then on, if you give even an 1/4 "
of gas pedal, car just sits there. very lightly feathering the gas and i can
coax it to move. I need to keep the rpms as high as i can and release gas apon shift or it stumbles all over again. It will stay like this till it sets overnight. I have replaced the maf and the tps. the cobe, btw is 41.
I have tested the tps and it checks out.

total frustration.
any ideas?

thanks
rodster