Steering Wheel and engine lockup

I was driving the other day and in the middle of a turn I lost everything--the steering wheel would not turn and the engine went dead. I drifted to the side of the road put it in park and turned it off. When I started it back up everything was okay?
Also, there is a lot of vibration in the steering wheel and it doesn't seem very tight.
Please help with any ideas.
2000 Chevy Tahoe LT.
55k miles

I'm about to make a posting with a similiar problem.
My engine does not cutout but on Right turns only, my steering locks up bad. I've had pump, EVO sensor and steering shaft all replaced on different visits (all warranted). The only thing that greatly reduced the locking up was when I got a new set of tires, but now it has returned after about ~10K miles of tire wear and is worse than ever. Going back to the dealer tomorrow morning (7/6), if something gets resolved this time, I'll let you know. Let me know of your success too if you get any.
2001 Tahoe LT

please let me know as well if you can get a straight answer from the dealership. Ive been having the same problem for a long time now and I'm sure one day I'll crash into the wall getting off the freeway because I cant turn my steering wheel. By the way, do you guys have after market wheels?