I have a 97 f-150 with a 4.6 that had problems, steaming and the transmission wouldn’t shift out of 2nd gear and I bought a motor and transmission out of a 2095 police car. It says 4.6 pol on it. Well I switched motor and transmissions at once,never split them up. Well now the transmission slips a little going into first but then it does fine unless you stop and take off again. But the main problem is it will run fine for 1/2 mile then it’s like it runs out of gas and will quit if you don’t let off the gas but if you let off the gas it will keep running until you hit the gas again. It won’t run farther than 1/2 mile while into the throttle. I’ve put new fuel pump new filters and I have a new crank sensor but truck isles and revs up perfect.

What could I do to fix this.

swap to a transmission your ecm can operate properly

Dang man there’s no other way? That sucks I wouldn’t change transmission for the truck