After leaving my car sit for most of the spring and summer, I am experiencing a spongy clutch pedal, sucking sound on pedal return. Also get an occasional hard pedal stop at varying points in downward travel. Unable to fully disengage clutch. I bled the system in various ways (one-way vacuum pump, Standard bleeding per manual) which did not cure it. Then replaced the master and re-bled the system, with no luck. After bleeding the pedal is hard for a single pass, but then goes soft again.
any insight is appreciated.