Rear Brakes Releasing Slowly

Does anyone know what would cause my rear drum brakes to release very slowly from a stop? It takes approx 10-15 seconds to fully release..The pedal also feels spongy? The master cylinder is about 6 months old and the rubber brake lines look to be in great shape..I have bled all four wheels.

Make sure the brakes are properly adjusted also.

They may be bled but will they pump up?

With the engine OFF, pump the brakes 5 or more time to purge the vacuum from the booster.

Pump up and then step on the brakes hard and hold. If the pedal starts to drop there is a leak or the master cylinder is failing.

I had the same problem not too long ago. On my car the rubber brake hose going to the rear end was clogged.

Thanks for the suggestions..I will give them a try tomorrow.