You should have no problem pulling an open trailer with the Tahoe, even without air bags. As everyone said, my first thought is you don't have it sitting on the trailer corretly.

I think they say 10% of the trailer weight should be on the tongue? Sportscar just did a trailer segment where they showed how to weigh the tongue with home scales. Do that before you spend a dime on anything else.

yes, if the rear of the truck is REALLY sagging maybe you have too much tongue weight. I think most of my race cars have had the middle directley over the front axle of the trailer. (as a rough estimate on where to position it)