You need to ensure that the engine is in good tune. It should have a good idle, AND, when you push the gas pedal a little bit, the rpm should smoothly increase. If in gear, the truck should accelerate smoothly WHEN THE GAS PEDAL IS DEPRESSED JUST A LITTLE.
There is a power steering pressure switch. When the steering is turned, this switch sends a signal to the engine computer. In response, the engine computer commands the fuel injectors (and, maybe the idle air control valve (iacv) to inject a little more fuel (or, a little more air, from the iacv). If something in this circuit isn't working properly, the engine won't get that little boost it needs when the extra load on the engine is applied, and the engine will stumble, or stall.
Inspect a couple of spark plugs. If any don't look real good, replace them.