When its below 60 degrees my truck has a hard time starting, and when it does start it runs rough, almost like its "missing" (if it were gas that is). Once it gets going it's very sluggish, however as soon as I can get the R's up to about 2800 it runs like a scalded dog and it will burn the rubber off of the 38's im running on it. But it can take 15 seconds of standing on the accelerator to even get it to roll and the R's dont go above an idle. I have changed glow plugs, and valvecover gasket / GP wireloom, I have changed the turbo and complete exhaust system with a 5" banks system ( even though it really doesnt seem like turbo lag)... Nothing seams to work. Please help.