Hi Ron,
I agree with Kevin as from the limited info you have given it could be an air leak somewhere. If you post Lambda and O2, that may give someone a better idea. You say "all sensors appear to be running within parameters" but what is MAP reading at idle? What about Ignition faults? have you checked that? I know your DTC was related to air inlet temp but in my experience IAT is not that important, although again someone with better knowledge of this system may correct me. Another possibilty is compressions, have you tested these or done a vac test? Mark also suggested engine breather. PCV valve will give same symptoms as air leak.
HTH's
Bryan.