OurPTGT,
Don't know what to say. My guess would be a loose vacuum hose, too. Check the one below the turbo inlet. When the boost gets up there, it can blow off. Mine did that with the MBC once, when I over juiced it.
BTW, I am boosting to 14psi in 2nd & 3rd, dropping to about 12psi as it nears redline. I get 10psi in 1st with no drop when it shifts to 2nd. I love it! No problems so far, knock on wood!
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PT-Dave
2003 Cranberry Turbo GT
Stage I, custom 3\" exhaust & Cowl Intake, Mopar BOV, Dual gauge pod w/vac-boost & A/F meters, Hood Struts, Yokohama ES-100\'s
Best 1/4 so far: 14.489 @ 93.65, best 1/8: 9.222 @ 74.261