problems with my 97 gs-t

[Boostnclipse]

I have a 97 gs-t with an upgraded greddy td05 18g turbo. My car is an automatic(which sucks, but oh well) Lately my car has been running like crap and ive been checking everything I can think of to fix. First of all even when my boost controller is turned all the way up my boost maxes out at 10 lbs then during shift drops to about 7lbs which it has never done before(used to hold 15lbs in low boost with nob turned about half way and during shift it would spike about 1lb and then drop back to 15lbs) Like Ive said Ive tried just about everything and my car just wont go fast anymore. Another problem I cant figure out is when I slam on the gas it feels like something in the rear is moving and locking into place before the car really gets moving. And once I put on the breaks it feels like it moves back forward. This problem really bothers me. Someone please help me!

 

[EvolvingGST]

U try looking for boost leaks? thats what it sounds like... remove ur intake see if there is shaft play too

 

[Rick4g63]

Check all vacuum line connections, especially the line from the wastegate actuator.