Riddle me this ,My truck runs fine until you put it in gear and go down the road ,1/2 mile maybe less ,sometimes only a couple hundred feet,it shuts off ,just like you turned the key off ,no warning no lights flashing ,no sputtering.then I coast to the side of the road put it in park it starts right up first try,this happens every time I drive it ,does anyone have any ideas on what this might be.

 

Check the fuel pressure.

 

Do you lose all electrical - ie. does the radio, heater fan etc. shut off? If so, I would start at cleaning battery terminals and then check your ignition key tumbler.

 

my gut reaction is the same as Ford Nerd. I would check the connections at the battery and solenoid, it sounds like a sketchy connection. Below is a photo of the solenoid in question if they're loose, make sure they're clean and tighten them up. It sounds like a bad connection, if everything goes out I'd lean toward the battery or solenoid connections being at fault.

 

I forgot about the starter solenoid! I've had 2 go on me before, 1 in a ranger and 1 in an explorer. Both times the trucks just wouldn't start. There are lots of posts here about distributors and fuel pressure, so more information is needed.