truck wants to stall and its sluggish

Have it read for codes, even if the check engine light is NOT on the computer will have stored information and codes. Discount auto stores will read codes for no fee. write them down.

If check engine light is not on try cleaning MAF sensor with MAF cleaner. Make sure to let it dry completely before reinstalling it.

Sounds to me like like an injector problem, especially concerning poor gas mileage. I would add some good fuel system cleaner to your fuel to clean out the injectors. Hot Shot Secret is a good one. They also make an Oil additive that is a bunch of detergents and emulsifiers for removing gum and sludge deposits.