Stumbling Idle at Startup

[Koa04]

I have a 07 GT fitted with a Paxton Non-IC supercharger and a few other mods. The car has about 25,000 miles on it and was dyno tuned locally in Hawaii.

Recently, I've run into a strange occurance when starting the engine. Every now and again, the car starts but begins to stumble while idling. Sounds like it is going to stall but it doesn't. It takes a couple minutes for it to get on it's feet and the idle returns to normal. During the stumbling, if you gas it, it will stall. This problem is very much intermitent, and only occurs about twice a week (no big deal I guess because the car is a daily driver). Still, it's enough to drive me crazy knowing something ain't quite right. I'm not sure where to start on the diagnosis. The car has not thrown code yet either. Any help would be appreciated.

 

[SpartaPerformance]

The days that it does this are they colder then others? May be a cold idle circuit issue, how long has the Paxton been on? Did you check for any air leaks in the intake?

 

[Koa04]

I live in Hawaii so it never really gets cold here. The idle issues that I read about on this forum don't really explain whats happening with my GT. I thought maybe it was a tune issue or maybe a fuel pump issue but the problem is so random it doesn't make sense. The S/C has been on for about 3000 miles with really no problems. I'm running the GT500 duel fuel pumps. I would think if the tune or fuel pumps were at fault the problems would occur consistently.

My tuner said he had a hard time setting a reliable tune. He said it was due to the air or air sensor or something (i can't really remember). I think it has something to do with the MAF being a draw through system. I think I read somewhere that the MAF is tempermental and is better suited for the blow through position. Maybe I'm wrong...

Anyways, thanks for your help and suggestions.