hughes performance transmission trouble

Ok, here it is. I have a 72 cuda with a 498 bb and a hughes tf727 trans, put the car together about 2 years ago when i ordered the trans and installed it i immediately had problems, started to tear things apart and i had fluid pressure problems......called hughes, argued for a few hours and they finally decided to warranty the trans just as long as i paid shipping fees. Got the a call from hughes and they said nothing was wrong with trans, were sending it back. Re-installed and it seems to work fine so i thought.....so much for nothing is wrong, well at least the car moves now, but here is the new issue: when the car has been sitting for a while and i fire it up put it in gear in any direction it barely want's to move i have to get the rpm's up quite a bit for it to get going after moving around a little bit everything seems to be normal shift well and so on, but once it's cold I'm back to burning a gallon of fuel to get her going again. any suggestion would be greatly appreciated. And if you need more info let me know. Oh and hughes built the trans and converter to the cars entire specifications.

72 plymouth cuda
498 engine
727tf 5000 hughes nitro stall manual valve body reverse shift pattern
4.56 gears
3400 pounds with me in it