I switched to the aluminum FLIRC Pi-zero case and my problem is solved! With continuous FLdigi use the temperature of the processor is not getting over 115F (46C) and no more shutdowns. That is a very nice package. Also, not seeing any WiFi issues, but I am seldom more than 6ft from the Pi so if it is slightly attenuated I am not seeing it on the router or the tablet.
=Vic=
Vic WA4THR