Alright let me start off by saying that when the car fires up it stubles and then fires decent but wont stay running unless you give it a little gas and then you can let up and it will idle, the needle will move around a tiny bit but not very much. After driving around and revving the engine high and then letting off and almost stopping it will die, it seems to like to do it right when i go onto the slant of my driveway for some reason, maybe it just knows where home already??? But anyway, when it does die the idle drops to about 450rpm and the stumbles and dies. Anyone know what could be causing this?

 

Could this be becuase of a fualty IAC valve?

 

If it seems to be running rich, check the vacuum hose connected to the fuel pressure regulator to see if it's wet. You can easily check and clean the IAC but I doubt it's your problem. You should also check your vacuum level, you could have a vacuum leak. Check the fuel pressure too.

 

Fuel pressure is 35psi at idle. We just changedthe vaccum line on the fuel pressure regulator so we know it doesnt leak or anything. I am running open headers with a y-pipe right now and when we first started driving the car it was running really bad and we had lots of black smoke from the y-pipe. But we changed the MAf sensor and drained the 6 month old fuel out and put new in and not a puff of black smoke comes out now and it seems to run a whole lot better. At the start up the engine wants to idle really low at about 500 rpms and when you rev it up and the idle comes back down it stumbles and almost dies and then regains itself. Maybe this can help locate the problem better. Thanks, Dustin.