Last week on the way to work it started to do the white smoke and knocking. It quickly went away. I took in to the stealer and they said there was a flash for it and an EGR problem. Well short story that didnt fix it. I brought it back and they scan it again and it still came up with the EGR code which I think is unrelated to the smoke(it was unpluged for the last 17000 miles). The guy didnt even look under the hood to look at the EGR. Well he said the EGR was causeing the white smoke and the knocking. I said WHAT? I said how can the EGR cause white Smoke. He just looked at me with a dumb look on his face. They replaced it anyways. Well I knew that replaceing the EGR would not fix the problem. I asked about the injector balance and he said they were great. So I took my pickup and 10 miles later white smoke and knocking. Got it home hooked up the trailer and head to SD well about every 20 min it would blow smoke and knock I just keep on going. About half way through my trip it started to do it again but this time it wouldnt stop and it went into limp mode. Scare the crap out of me. Pulled over and shut it off and resarted it. Drove fine for the rest of the trip down. I took it to the dealer in Spearfish, SD they hooked up the Tech II and right away and said that when it went into limp mode there wasnt enought psi in the fuel rail. He buildt up the pressure and it held fine with out a problem. Fuel regulator issue he thought. I drove the whole weekend and not a problem but on they way home same thing white smoke and knocking every 20 min or so. I pulled over and shut it off and restarted it and all is good for the rest of the trip home. Waiting to get it back the the stealer and see what they say this time. Any ideas why the smoke and knocking clears up after I restart it.

Fuel filter changed about 2k miles ago

do a search for white smoke in the LLY section.. many posts on this.. most lead to injectors.