Vibration

Hi I have a 2014 Toyota Camry that’s been
shaken in the gas pedal, worse at around
40mph. I’ve taken it to the tire shop and
had it balanced and rotated and the back
brakes done. I still need to do the front
ones but took my car home and although
the vibration seemed better, it was not
gone. Took it back and had them rotate
and balance again and try to figure it out.
The end result that they could tell me is
that my tires, tread or belt? could be
uneven causing it and to get two new tires
to see if it changes anything. I will say the
the first balance and rotation helped and
having them do it again has actually made
it worse. Any suggestions before I do more
work than is needed? Thanks