2002 Powerstroke not starting but GPR seems fine.

[bldrroddy]

I have a 2002 F-250 Powerstroke that is not reliably starting. I can get it to turn over, but generally just get a lot of white smoke and it rarely starts. It will start if I plug in the block heater for an hour pre-start. When the truck finally does start, it runs great. I recently replaced the batteries with brand new heavy duty Costco ones to no effect. The starter has a intermittent solenoid, but when it is working the starter seems to engage strongly. Here is what I have done to troubleshoot:

1) I have checked the glow plug relay. Made sure the left terminal was reading 12 volts at all times. The right terminal was reading zero with the ignition off, but 12 volts when on. Did a two minute test and saw less than a .1 voltage drop between the GPR terminals with the ignition activated and relay engaged. The relay resets after about two minutes which seems correct. The engine had sat overnight when I run this test.

2) I jumped the two terminals with a heavy gauge cable for 90 seconds with the ignition off. Then tried to start the truck. Did not seem to help.

3) I pulled the glow plug connectors from both cylinder banks and tested the resistence of all 8 plugs. I used the negative battery terminal for ground. Here I noticed something that is possibly interesting. The driver side bank's four plugs all showed 1.4 ohms while the passenger bank showed .5 ohms for it's four plugs. I would have thought a bad plug would show infinite resistance, though the .5 ohm reading seemed out of spec. Do I have a problem here? Potential bad ground on passenger side?

Any help or leads greatly appreciated!