My 02 F250 takes forever to start if not plugged in. Even when it is 60 degrees outside. When changing oil, I found a green tint to the oil. I know that means fuel in the oil. When it does start it blow lots of white smoke for a few seconds. Other than that it runs fine. After I changed the oil, I noticed that it would miss between cold and hot for a few days and now it is fine. I had glow plugs tested and they are all ok. Could it be the GPCM? or is there a different concern?

 

Could be the injector orings...

Also, get the truck on a scanner that works with powerstrokes (AutoEnginuity) and watch ICP and Duty Cycle % during cranking...

 

white smoke is unburnt fuel. Replace the glowplug relay or use your aih relay to run your glowplugs to rule out the relay. Then test your glowplugs-they are pretty easy to change.

valvecover gasket is reuseable and use only motorcraft glowplugs