high pyro temp/low boost/weak engine brake

[tree98]

Post a picture of the turbo side of the engine. Also unplug the EGR valve and see if the check engine light comes on, if it doesn't come on then the engine is likely demandated and probably quite badly.

Something else that can cause low boost and high pyro on the 870 is a stuck / sticky turbo VG ring or actuator. This will also cause weak jakes. You can apply shop air to the actuator and measure the travel, I can't remember off hand but I think it's supposed to move 10mm ?? You can look it up on quickserve.