Hello all,
This post is for a friend of mine, He just bought a 1988 mustang hatch with the 5.0 and manual trans. The car will crank but, it revs high and then the revs drop until it cuts off. We have checked the timing, and firing order numerous times. For some reason it sounds like there is a popping noise coming from the airbox. Any help will be greatly appreciated

 

reving high could be vacuum problem! ...check for a big leak...

 

vaccum leak or Iac motor bad or stuck or it is not running on all cyls

 

x2 to the vac leak check all around.