Out of curiousity, did you ever get this issue resolved? I see you traded the car.
I have some issue with my trans shifting right now, but research here leads me to believe its a shift solenoid.
03 SVT #442 - (LEMON)
05 ZX3 SES, SVT susp, etc (SOLD)
07 ZX4 SES, SAP2, IUP, FRPP, Pista's, Tint 73k