throttle body problem..ls2 06 gto....

[zingercustoms]

Hey guys, need some help, 2006 GTO ls2....I have weird deal where the first time I start the motor the throttle body is unresponsive...the tps is working cause when I rev it up it does add fuel and rev slowly but the throttle body doesn't open besides by the vacuum created by the motor. if I shut off and start again the throttle body works right. if is sets a few minutes it does it all over again...I am afraid it might do this while driving, maybe it won't...the weird thing is I can turn the key to the on position before start and hit the pedal and hear the throttle body open and close but as soon as I start it, it stops responding. then shut it down and it works the next start.......