we just had an engine rebuilt because of loss of power over a highway road trip and now, since, the rebuild have experienced very similar problems with this vehicle (1999 Ford, Ranger 4X4 3.0. wondering about the vehicle’s computer?
Could be. You should be getting a check engine light, but a failing computer may not store the codes. My first step would be return to the rebuilder/installer. Should have some sort of warranty on a fresh rebuild.