98 Explorer EB with high-end "Mach" radio (the one with the display issue)
with Tape/CD/CD changer and steering wheel controls.

Recently the radio has begun shutting itself off all by itself.  I turn it
back on and it comes back but then shuts off a while later.

I don't think it's getting hot as it isn't on long or turned up too high.
It seems to only happen sometimes but when it does happen it is persistent.
IE: I took it out for a short trip and it shut off 6+ times.  After it was
parked and restarted it worked fine all the way home.

I was thinking the steering controls (sometimes they glitch) but there isn't
an "off" button on there.

Any idea what could cause this?

Are there any "codes" on the radio I could look for (and how)?

Thanks.