Overheating when stopped

Hi 2009 Tribeca - 2 years ago had HG done, waterpump, rad, Tstat, and
heater core flush (was blocked). Been fine for 2 years, now overheating
issue is coming back but I am catching it early and want to nip it in the bud
and hope it is something simple. Recently I have noticed that after the car is
warmed up and I stop at a light my temp will slowly rise - after a minute or so
it is up to 106C (223F) and goes up one tick over normal on the gauge on
the dash. If I rev the engine it will go down to 92C (198F) or so. Fans are
working correctly and kick in when needed - no obvious leaks. I also note I
am not getting heat from the cabin (some heat at lowest fan level but dies
quickly if I turn the fans up). Temp stays in the 90's C while driving. Just had
the system flushed and Tstat replaced (was an oem Stant - I know don't
shoot me...). Thoughts on next steps - thinking of bypassing heater core to
rule out that? Possible air lock - but why before and still after flush would
that still happen - and wouldn't the car self bleed the air out after a bunch of
warm/cold cycles? Thanks in advance for any help/advice