CM870 won’t start when engines hot

[MattSierraServ211]

I am currently having much the same issue on the same engine in a KW. And i have already replaced just about everything you can regarding the fuel system. Had initially found an injector cup with a huge chip out of it, i do believe that was the main culprit of all the air in the fuel return we were seeing. So the head, all injectors, lift pump, fuel cooling plate, fuel pres. regs, metering and timing actuator seals, pulse dampner seals on back of the fuel module, etc. have all been replaced. And i am still getting air in the fuel return straight out of the module. Clear as day going in, air mix coming out. The warmer it is, the more air you see. i have multiple cummins manual books but the diag. for an air in fuel problem is as vague as can be.

Anybody got a suggestion that could direct me to the light at the end of the tunnel?? Lol