Robert Peterson

The truck has a fuel water separator and I have run additive in the truck and seems to make no difference.

what kind of temps are you talking about? May have some water in the fuel. Freezes at 32 and is slightly blocking fuel system.

Are you putting any additive in, especially now. I use Diesel Service stuff. Have heard good about Howe's

Between the air temp up, and the heat from fuel return, yes it will run better.

I drive a 99 RD with an E7 400 with a 8 speed behind it, since it got cold the engine does some strange things. When running up through the gears sometimes it will only rev to about 1700 then the torque falls off badly or it will start to "hunt" for lack of a better term, or if I stay in it sometimes all of a sudden the power and torque will come back. It seems when the outside air warms up later in the day it will run alright. I'm leaning toward a bad boost sensor, but not sure, can I get some help on this problem. I do not think it is a fuel problem because I don't think the air temp would affect that.