Elantra 2016

I have a 2016 Elantra Limited that stalls after 10 minutes when I drive it/
Warms up. If I am going in a higher speed and remove my feet from the
pedal, you can see the RPM dropping and if I don't press the pedal couple of
times to raise the rpm, then it goes off. But If I press the gas pedal couple of
times, the car runs normal for a bit longer, then once I remove my feet it
stalls again! When it's cold, it runs perfectly fine! The issue gets worse when
AC is on which makes sense because it is warming up faster/ more load on
the engine.
I have changed the spark plugs, coils, fuel injections, timing chain with
tensioner and guards.
Hyundai dealer told me they were sure it was quitting on me because of the
timing chain, well that didn't do it!
I am running out of options here, any idea please?