JDKid

I got a 1gfe from an altezza for an engine swap. But im having issues moving forward. It starts up a lil slow, but it does start. When its cold i get to go anywhere. It idles fine. But when the engine hits operating temperature, and i let off the throttle it shuts off, it starts back up but it doesn't stay on if im not feeding it gas, it idles really rough if i do mange to get it to idle. Ive been told its an exhaust leak but ive sealed the exhaust. The issue still persists.