CM870 High Pyro/Low Boost intermittent under load

[nmazpeterbilt]

I read a previous thread that was somewhat related to this but I don't feel exactly the same. I have a CM870 all stock. It is 500 hp. It is a Recon that got put in 2 years ago. Whenever there is high ambient temperature and under load the pyro temp will climb up for 900 to almost 1100 pretty quickly and at the exact same time the boost pressure reduces to about 26 pounds. It will stay there for 10-30 seconds and then pyro comes back down and boost goes back up. This is accompanied with some black smoke. During the winter did not have the issue. Do not get any codes or warnings. The pyro is an external unit, not coming from the ECM reading.Trying to get this figured out while it is under warranty, but of coarse cannot be replicated at the shop. They did replace the Barametric/temp sensor thinking that may be it, but that didn't resolve the problem.