No idle, has power

It sounds like you have a bad coil. When you get into the throttle all the way, your truck runs fine because your engine is forcing a ton of current through your coils and plug wires. when your just putting around, its not forcing so much current theough, so if there is a mass of resistance somewhere... ie... a bad coil, or even a bad ground wire from the engine to frame, your cylinder wont get enough current to fire the plug hot enough to burn the gas inside the combustion chamber. You could also have a hairline crack in your plug, or a short in your wire. both things will be fine under full throttle, and both things will appear to work fine just by looking at them.

just do a switcheroo from cyl 4 to cyl 1. if the problem moves with the plug, wire and coil, then you know its one of those three things, and you can start weeding it out from there. good luck, and keep us posted.

That would make sense because when I tested the spark they sparked orange and not blue