After some testing it seems that PF3 saves the selected PTT key that is written to the ini file as long as MCE is NOT RUNNING.
If I start MCE after I have configured the PTT in PF3(and it is running connected to FSX) OR if MCE is already running when I configure the PTT in PF3 and load it into FSX, in both cases the PTT selection fails "to stick" in the PF3 ini file.
Could MCE be over writing PF3 ini file or duplicate assignments somewhere between PF3 and MCE?