i crank it and it goes on. then when the revs come down it dosent catch idle it just shuts off, the only way i could keep it on is if i hold the gas for a lil while, then it idles buy itself. i replaced battery, alternator, ignitor, last week

 

What motor? What ECU? Any mods?

 

When the exact same thing happened to me it was the injector o-rings... sniff around where the injectors are for a fuel smell. That would inidcate the problem.

Also you might have luck getting it started if you turn the key to "on" and wait a few seconds before turning it to start.

The o-rings are little tiny rubber donuts you put on the injectors, and mine were rotted away and crusty. Cheap to buy, easy to install. Replace your fuel filter too if you havent lately, since you'll have it all apart.

 

i to also had exact same problem..only for me in turned out to be my distributor..car would start and run if i gave gas but would die right after..replaced it and never had problem again..