Need Help

[MUSCL GN]

I cannot figure out why the car keeps stallin out every time I put it in gear. The car is fine at idle and all #s from scanmaster read ok--No codes or nothing. But as soon as I put it into gear it stalls out and dies. Is this a vaccuum leak? Any ideas would be appreciated. I do not think its related but recently I hooked up the timing wires to the trans plus- I was running for a year with just reg trans-no problems. Thanks,