losing power on hard pull

[Chamberpains]

(11-15-2019 )tdawg Wrote:  jakes jump up to 28 and then comes back to 15.

If this drop happens fast and/or intermittently and NOT after a long lessening jake downhill (15 psi can be normal 3rd stage at low rpm 1300 or less on slight down grades) then this strongly points to a faulty turbo actuator control module. It's the red box with an air line in and out and a 3 wires in to a plug under the air compressor on the driver side of the engine. If you can get you hands on a known good one and swap them out for a good long test drive, it would be the cheapest simplest way to know if this is the culprit. They are expensive $900 part and if it needs replaced you definitely want to buy 100% new GENUINE HOLSET.