2001 F350 low power, low boost, P1247

[4x4 Nut]

Hello, I have a 2001 F350 cab & chassis (170,000 miles) that for a while now has had low power. It's TERRIBLE when cold. If parked in grass or dirt where the tires would sink in just a bit I don't know if it would pull itself out while cold. Codes show P1247 (turbo boost) & P0380 (glow plug control) which I don't think are related. The truck starts fine, idles fine, & runs smooth- just low power. The wastegate actuator is in tact & starts to move at about 5 PSI. The MAP sensor hose is fine & in place. I don't see any definite leaks on the boost hoses. Up-pipe gaskets are just slightly leaking (just a trace of soot).

I've checked it with AutoEnginuity. HPOP pressure is good, boost tops out about 11 PSI, EBP sensor shows good range of pressure movement & the sensor looks recently changed.

Something sounds a little off when accelerating. It sounds like it could be a air leak, whether boost or exhaust, but I don't see anything. I'm wondering if the turbo itself is faulty.

If anyone has any input, I'd appreciate it. Thanks.