Had a vibration while braking, checked brakes and the rotors were grooved. Replaced the rotors and pads (frt). Back rotors and pads checked out ok. Still have the vibration, thus somewhat better.

The vibration occurs around 20 mph under braking. Worse after continous stop and go driving (hot).

Any suggestions on where to look? Thanks.

 

Sounds like the rears are warped.
I will bet you feel the vibration through the brake pedal.