93 ford F150 tranny issues?

[Nick]

K, i just got a big ol 93 Ford F150 XLT that im ganna be goin muddin with... only issues, i need shackles and dont know the best ones also a good deal on some leaf springs so i can jack it up about 6 inches, cuz i kinda wanna stay road legal at the same time, and heres my other problem, the tranny... my friend just put a rebuilt from oil pan up 351 V8, but my tranny aint workin the greatest, had no issues with it before, but now when i put it into drive, it doesnt wanna move, also with reverse, but if i just let it sit for a little bit, i can put it into drive and drive it for like half a mile and the tranny will start actin stupid again, could any one help me with this problem, thanks