okay heres the problem im having, i just did an s4 motor swap on my 87 Rx7 because the other motor was warps due to the previous owner, so i completed the swap but when i start the car it will try to run and idle funny for a couple seconds then die. so what would cause this? i need some help fast any idea? because i don't want to keep driving this crappy 626. thanks appriate it.

 

Make sure the AFM is plugged in, and look for vacuum or air hose leaks. Other than that, could be a dozen different causes. Download a copy of the factory service manual from one of the links in the 2nd gen FAQ and run through the troubleshooting matrix.

 

From my experience, crank and die and idle and die problems are caused by vacuum leaks. Make sure all vacuum lines (and there are a bunch of them) fit snugly at each end and are not brittle or cracked. Make sure the gaskets at the Upper intake and Lower Intake manifolds are not worn, torn or otherwise sucking air. Once you've eliminated vacuum leaks, go on to other things.

Clogged fuel filter
Clogged Cats
BAC not working right
TPS not correctly set or malfunctioning

For idle problems you have to eliminate the possible culprits one at a time.