1993 rx7 engine stalls(streetported)
 

hey guys im kinda lost on this one... just did a street port swap in my jdm rx7 went from a japanese engine to a american engine(very hard to get it all wired up)... got it all running and it will start but now it likes to stalll....here are symptoms (worsen from cold temperatures)

bit of a hard start (worse in cold)
idles fine untill it drops by it self and then it stalls...it wont stall if i keep rpm up
after high speed runs it willstall as well
might have a vacuum leak(not sure yet)

other than those symptoms its fine... so im not sure what it could be im lost so any help willbe great! get back to me thanks!

so anyone?