While running my truck lights dim and then get really bright. The same can be said about the idile of the truck. It will idile low for a little bit then the idile will go up. Truck idiles @ 750rpm. Any help would be appreciated.

Tree

 

All the time?

 

I would have to say its your grid heaters cycling if it only does it when its cold

 

If only doing it when the motor is cold, it's the grid heaters cycling, and it's normal.
If doing it when the motor is warm, it may be the A/C cycling, which will happen if the defroster setting is on. Turn the heater control to floor, and it should stop.
If the grid heaters are cycling when warm, you have a problem to fix.

 

All the time. That's what I was afraid of. Would this have to do with it not starting? Thanks for all the info.

 

Say fellas, Do the grid heaters sound like an electric fuel pump?

 

The grid heaters have no sound, they are very similar to a toaster, without the bread popping up.
I think you are hearing the A/C clutch kicking in. Turn off the defrost.

 

Check. No defrost on. Thanks