07 lsj-t problems gen 3 build
 

Okay so ive been having this problem for about 2 weeks now. I start the car and idles for about 4 seconds then dies like if its choking/sputtering. i have checked fuses, fuel pressure, compression, fuel filter, spark plugs, vacuum leaks, maf, fuel pump, throttle body, map, and everything in between. Also if i start the car and give it gas it wont die on me but only as long as i give it gas. I can drive it around but i jave to constantly be giving it gas. What could it be? i cant figure it out. And i sure the tune is not the problem as its being tuned by alan. Any ideas or thoughts? Please let me knw:/

That's a tough answer with the info given. Throttle body perhaps.

I swapped out the throttle body 2 times with working ones from two cars. Im using an le5 2.4 throttle body on a saab manifold if that makes a difference. also swapped mafs and map sensors and still same problem. It doesnt even throw a code other than random misfire and ac pressure switch which i wired to monitor a/f ratio.

vacuum leak

What's your blow off valve spring rating? I would guess it's too soft and you're opening the spring at idle. I had a similar issue after swapping to turbo.