Does this sound like a transmission problem

I think your shifter linkage ON the transmission is out of adjustment and needs adjusted. See if you can put it in neutral and start it.

take a look at the mounts for degradation of the butyl-rubber and possible change the transmission and motor mounts,,,,,okay lookin' this bad boy would go to hell but quick...see what's left of it~ https://www.google.com/#q=2004+GMC+Envoy+transmission+mounts&tbm= shop&spd=10799775799728707595

do you think she should check and clean ALL the grounds first judge?

tuff4x4 is going where i would have went. Before it broke do you think it shifted from park. Will the vehicle roll right know?? These have a cable runnning from the steering column down to the tranny to shift. The cable is bolted to the tranny and attached to the shift linkage on the drivers side of the tranny. The P-N safety switch is mounted to this shift linkage on the tranny. You need to roll under there and check this. The issue should be noticable if it is here (except for a internally broken cable). Try turning the shift linkage counter-clockwise (top forward) untill it stops this will be park. May need a tool for leverage. Try starting. If it starts shut off, put the shifter in park and re-attach the shifter.

linkage came out of arm on trans by now I'd assume you've fixed it

Mine was doing same thing it was the battery connection

It's the gear shift cable.

I was driving when I park and reverse my car it was fine when I tried to reverse the shift would not reverse drive the car still cut on I have a 2003 gmc envoy I called on star they did a diagnostic they said everything is fine my transmission no problem what is causing my car not to shift I just tried it shift but won't lock

You fine the problem?

Had the same trouble last night. Sled under my truck today and saw this....shifter cable needs its bushings replaced.