Is this a vacuum leak?

[XFD Raven]

Alrighty, I've finished my SR swap and debugged the TPS bug that was my other thread's topic.

Now, I'll start her up and it'll have a hard time and sputter around 500rpm. If I'm delicate about giving it gas, it'll struggle up to 1500rpm, then you hear the turbo start to pickup and she becomes real smooth and generously climbs as high as I want. After keeping it at 2000rpm for a little bit, I'll let up on the throttle and the RPM drops down to 850-900rpm idle, but theres quite a bit of roughness. Now, the interesting thing I noticed is that if I floor it and let it climb to say 4000rpm then immediately let up off the gas, the RPM comes down and dips to 500rpm again before recovering to 950rpm.

Now another interesting perk is that when putting it in to 1st and starting to go, it has no power until 1500 rpm. When I say no power, it takes 15-20 seconds to get to the barrier and then starts to go. I've double checked all the tubing and couldn't find anything either.

Any ideas or suggestions?

(S13, Redtop 5spd, SR20DET)

[180fan]

time to poke around with some brake cleaner at the seams of the intake tract.