03EBZ06

I would start looking at codes from the PCM. How about a loose reluctor wheel or cam sensor problem? I don't think your problem is nitrous or necessarily tuning. I mean you said it was a problem during normal driving. Also, a 1000psi bottle might leak down over time.

Dynospeed

iTrader: (3)

When I started running anything colder than a -9 I had to start putting more and more timing in it at idle to keep the plugs happy. I think you have something else going on for it to foul them instantly after trying to spray them. What's your jetting and fuel pressure? Does the car start to pull strong before it breaks up? Is the bottle good, is it open, is the nitrous noid opening? Is the kit used, what's bottle pressure?