2012 Ram 1500 dies & restarts on highway

2012 Ram 1500 quad cab w/4.7L, 6-spd auto, 4WD. Dies
while on highway, cruising between 55-70 mph and at
operating temp OR when parked and cold on aftermarket
autostart.  Only seems to die when throttle is steady. When
on autostart, dies after RPMs drop below 1,000. Completely
random, not consistent. If on highway, I can drop 2 gears on
transmission manually and get engine to restart as torqe
converter is still locked OR stab throttle pedal to floor and
engine restarts. Red lightening bolt shows momentarily on
dash digital display. All electrical still working normally.
New spark plugs (all 16), new wires, new belt, new battery
with hard reset in April 2018. Dealer checked alternator,
says good and claims entire throttle body is bad ($600).
Independent shop checked and 'mapped' fuel pump, says
good without odd current spikes. Has NEVER popped any
codes when this happens. Ideas?

And does Chrysler still use an ASD relay in this model?