Hi, if you front Calipers are Lockhead then as they get older then they can develop sticky pistons. I have been told that this can occur due to the casings deforming and replacing seals and/Pistons will not nessisarily resolve it. If you are getting a hunting feeling when the car is free wheeling then it may be a slightly warp disc, this can be felt as a brake judder when braking lightly to reduce speed it may emphasise the judder.
Jack the car up, and put on stands, remove front wheels and spin each disk with a firmly anchored price of metal just touching the outside edge, you want the disk to spin true no wobble which will show if it rub the metal as you spin it.
If the disks are not warped then it's probably one piston sticking causing uneven pad pressure one the disk. You could try Remington the calipers and replacing Pistons and seals to see if this solves it.
