2 questions - A/C, traction control

I have a 2003 Yukon XL Denali with 55,000 miles on it.

Sometimes the A/C will blow cold air. Sometimes it will blow hot air. Any ideas? Dealer says they can't find anything.

Also, the traction control system will randomly activate cutting power to the accellerator. Not good in traffic. Again dealer says they can't find anything. They "updated the computer" on the truck and the guy said that should take care of it.

Any other ideas?

Thanks!