if anybody has read any of my posts, i was having tons of problems with my EPC light coming on all the time and sending the car into limp mode. i finally had enough of it and removed my mbc. to start things off, i got a speedtuning chip back around christmas and for some reason, it still only made stock boost sometimes. sometimes it would boost like a chipped car (about 16 or 17 psi) and then sometimes it would only boost 7 psi like a stock car. thats why i installed a mbc in the first place, to get a consitant boost level. well i got tired of all the problems i was having so i took out the mbc and let the chip control the boost. i am back to having the same issues as before (inconsistant boost) but i also have some other wird problems. sometimes i have no boost at all. i look at my boost gauge and it like freezes or something. i wish i had a video camera to show people what i'm talking about. i accelerate and watch my boost gauge and it literally doesnt move at all and i have no boost...and then sometimes it works fine. also sometimes i have boost but its really slow and lathargic feeling. sometimes ican go full open throttle and watch my gauge and the needle will just creep up to full boost and then when i shift it just creeps back down to 0 on the gauge. its really weird. it moves slower than my spedometer needles does. i have no idea what causes all this weird **** on my car, but its really getting annoying. its possessed.

 

you could check a few things:
* wastegate actuator - check with hand-vacuum pump.
* vacuum lines for slits/cuts/holes.
* boost piping from airbox all the way to throttle body.
* intercooler for leaks (oily residue is a hint).
* diverter valve for broken/ripped diaphragm.
* turbo shaft for in/out play.
* do a TB alignment for good measure.