Things to look at:
1. Turbo/intercooler hoses for leaks/tears - must remove from vehicle to check and while off check airbox to turbo hose for tear on bottom just in front of turbo and check turbo wheel for play (very slight for/aft ok; side to side should be zero or maybe a bare feel of play)
2. boost pressure solenoid - see my post at
viewtopic.php?f=5&t=70602&p=757348&hilit=boost+solenoid#p757348 3. gummed up turbo variable vanes - per GDE You can check the vane functionality at idle in park. Underneath the vacuum actuator on the turbo is rod extending downward connected to the vane mechanism. If you pull off the vacuum line at the turbo, the arm should drop about 1/2 inch and then raise back up after reconnecting the vacuum line. It is a bit difficult to see the rod, but this is the easiest method to check for proper VGT vane moevment.
4. possible pinched vacuum line running from turbo vacuum supply on behind coolant tank that might could be pinched when pulling/installing tranny while doing TC replacement. Also any wiring plugs that might have been pulled loose during that process.