'04 SLE engine stalls when shifted from D to R and from R to D, only does it when a/c is off, starts right back up, otherwise runs smooth, 4000 miles, no codes, dealer unable to resolve - Any ideas?

park/neutral safety switch?? take it back to the dealer or a different dealer and have them look at till its fixed, that is what your warrenty is for ......use it

Dealer was stumped by it only happening with a/c off (solution I guess is to always leave a/c on ) - I was just hoping to be able to provide some input in case I get the same response from the next dealer.

Dealers have computerized access to GM techies back at the factory.
They have to be able to figure out these kind of problems.
They can link the computer diagnostics up directly via the internet to troubleshoot.

Cool, thanks SilverBullet, now at least I have something more to discuss when they give me that blank look.