I have a 2003, f-350, 6.0L with a K&N Filter.
While driving the glow plug light comes on and the power is shut down. After a few seconds the power comes back and it won't do it for a while.
No codes.
I replaced all of the glow plugs and wires.
Anyone have this problem or idea on what's causing this?

Thanks

 

You need to see engine voltage live while it's having the problem, meaning you need a either an OBDII gauge:
https://www.ford-trucks.com/forums/1...eral-info.html

Or a voltage gauge wired to the batteries directly:


Check voltage to make sure the PCM isn't dropping when the problem happens. While you're waiting on a way to check voltage running, start checking the engine wiring harnesses for chafing or exposed wires that could be shorting.




I have an iPhone so I use the DashBoss:
DashBoss | A Brain Scan for your Vehicle

If you're an Android user, a Bluetooth OBDII dongle and Torque app is what you need:

 

Had my alternators rebuilt but now the voltage starts off normal but quickly increases to 17+ volts.

Any idea what would cause this?

 

Your truck came with dual alts? Either a bad rebuild and the voltage regulator is messed up, or something in the PCM isn't right in regards to the dual setup.

I don't know exactly how the dual system is controlled, so to get a better answer you can either start a new thread in the 6.0L engine forum, or ask a moderator to move your thread there:
6.0L Power Stroke Diesel - Ford Truck Enthusiasts Forums