I just finished putting my old motor back in after the new one went bad. Once it got running with the old motor in I had this bad vibration around low to mid rpm’s????? I have no idea where it was coming from and then the whole car stopped. What happened was I tapped the gas while driving, the car slowed down and then it would only move when I revved it up a lot. Whatever is wrong the car only moves when I'm in gear and I give it a lot of gas. If I try to pull away normally with little amounts of gas the car doesn’t move. It revs up, but not until around 3000rpm's does it start moving.