[142 Guy]

When you replaced the pads I expect that you would have had to press the pistons back into the caliper body to insert the new pads. If the pistons retracted into the caliper body smoothly it is unlikely that you have a problem with the calipers.

Since you replaced the disks, was the mating surface on the hub for the caliper cleaned off to bright metal? If the surface is not clean the disk could be sitting 'high' on the hub resulting in inadequate clearance between the disk and the outside pad. With a wheel off you can insert a feeler gauge between the inside and outside pads and the disk to determine if the retracted clearances are significantly different (lack of clearance on the outside surface indicating that the disk is not sitting correctly).

If the rubber flex lines are of unknown age, grumpydad's suggestion of internal swelling in the line preventing retraction of the pistons is a possibility. However, it would be unusual for both front brakes to develop a swelling problem in the flex lines at the same time. However, if your old pads were really worn that might have provided additional pad - disk clearance which masked the swelling problem.

Finally, is the brake pedal retracting to its normal position? If the brake pedal is not retracting sufficiently fluid pressure may not be dropping enough to permit complete retraction of the pads.