Why does my turbo act up when it's super cold out??

[Adam711]

Hi all and thanks for looking. I've got a 2006 6.0 with 75k that's a gem until the temp drops below 20 deg F. Below 20 deg but above 0 deg, turbo builds pressure as it should but I cannot get it to make more than 21 psi. Hold on this get's weirder.. If the temp is below 0 degrees, the turbo will make normal pressure (all the way up to 30 psi) BUT turbo lag is so terrible that it often takes 5+ seconds to start making boost when I step on the throttle. Makes no sense to me. Again, above 20 degrees and it's great, but below that it's temperamental and throws trouble codes left and right. The codes are P0069 Manifold Absolute Pressure Barometric Pressure Correlation and P0299 Turbocharger Underboost. I usually also get one called Low Exhaust Backpressure. I'm planning on taking the truck into my local dealer but thought I'd check here first. Seems to me I remember reading a post a while back about a similar problem and the dealer ended up replacing the turbo. I live in Minneapolis and right now it's -10 so this is a daily issue. Thanks all for the replies in advance!

[Dieselkid]

Veins are sticking, pull the turbo out and clean it.