1988 mazda rx7 NA , engine had been rebuilt, new fuel tank, pump, and bypasses fuel filter, to get it to run and stay idled. Car starts, goes to high idle then stops. Checked vacuum leaks and everything looked good, and still high idle.

 

welcome to the board.

2 months old ... hopefully, you've resolved this, but if not, i'm thinking you should still look for a vacuum leak. if possible, post a video of the car doing it.