When I park my truck on an incline and have low fuel, the truck will start and then stall out. Once I level park and wait twenty min. the truck will start and all is okay. Happens occasionally. Hasn't stalled while in traffic. Lately, I think the engine noise is louder when on the road. Not sure if this is revelant to the stalling problem.

First off leaving the tank low on fuel is a bad practice for several reasons.. modern vehicles have fuel pumps inside th fuel tanks... they rely on the fuel to cool them or they burn out soon... second tanks kept low on fuel have far for condensation issues causing water in the fuel.

How low are we talking.. perhaps its low enough its sucking air.if only for a moment as fuel sloshes.

Smoothy is right you should never go below a 1/4th of the tank. A full tank lasts longer anyway. If you are on an 'incline' with that low of an amount then its not near the fuel pump. That is why it doesn't work when on a hill