Acceleration drops out- help!

I'll try be be short yet descriptive.  2004 Sebring Sedan 98k miles. Regular oil
changes.

Backing out of a parking spot on a cold day after work the gas pedal stopped working,
more so the gas pedal works and the RPM's function properly and the car never
stalls, but there was no acceleration with the pedal.  I had to turn off/on the engine a
couple times before the car would move again.  The car functions properly once it's
driving.  It appears to happen more often when it under 20 degrees out.  The first time
I took it in, the mechanic said no code showed up (there is also no light on the dash
indicating any issue) They cleaned the throttle body and said that should solve it.  It
did not.  A couple people have suggested the trans is going due to last time this
happened, and finally accelerated, I could feel a thud/it finally clicking into gear.

I am open to advice/similar situations, but wondering if I should start with changing
the trans fluid/filter and going from there or does this seem something more extreme
like the trans going bad?

Thanks.