Typically, no matter how bad a person is at driving a stick, it's near impossible to stall it while moving, especially at highway speed.... momentum of the truck will keep the engine turning. It's either a sensor issue (i.e. IAC, TPS, MAP, or speed sensor), or tune up issue.

 

Maybe one of those wires hanging down connects to your Speedometer.

 

just give it a tune up and see what happens, cap/rotor, wires, plugs, air filter, engine oil/filter. and to correct big bryant, the speed sensor is located ON the rear axle, not in it. look and see if you can find a plug around the top of the axle, see if its connected. maybe the wires hanging down were disconnected from there, or the sensor just could be bad.

 

I was told the speed sensor is in the tranny tipically not the rear axle, but could be wrong.