ls1charged

iTrader: (8)

Car is a 99 SS with a 5.3 swap and turbo kit.... been working on the tune for a couple weeks, the car drove and idled perfectly fine NA.... been tuning for boost which the car still drives great but when the car is cold, it surges and struggles to stay alive, 200-900rpms... when it's warm it fires right up and idles fine... however when I throw it into neutral to coast to a stop, the idle dips down around 500 and comes back up to 900..... Did some searching but came up with all kinds of stuff ie bad maf, iac, tps, vacuum leak etc etc I am skeptical of my brake booster line cause I have a vac distribution block spliced in but other then That? Any suggestions?

JoeNova

What did you change between the N/A and boost tune? Nothing should change unless you physically changed hardware like injectors.

Are you still running O2 sensors?

ls1charged

iTrader: (8)

That reminds me lol I did put in a 450 pump i had because my 255 crapped out on me randomly.... i checked at the rail and it said 68psi but doesnt mean the stock regulator is being consistent with so much pump...you think fuel pressure to high could cause my issue?