Rough running 99.5 7.3 until warm

[RRlocoENGR]

My 99.5 7.3 in my F350 crew cab dually runs rough when first started, worse the colder it is outside.

If I plug the block heater in, it runs fine. If I crank it and allow it to warm for about 15 minutes it runs fine.

If I drive before warmed up completely, it shudders and has very little power. If I shower down on the throttle briefly, the rough running goes away immediately. So, either being warmed up or showering down on the throttle solves the rough running.

Injector problem or something called a pedestal valve??? problem? I have heard that these motors have some type of valve on the base of the turbo that reduces power when cold???

Truck runs fine when warm, but a pain when cold!

Thanks for any input!