2nd Gen Non-Engine/Transmission stiff brake pedal

[S D Smith]

I recently purchased a 99 3500, soon afterwards I began to notice a light power steering whine, fluid level was OK and everything was working so I let it go, so I could put money into what I felt were more important maintenance issues. The previous owner apparently didnt believe in maintenace and combined with plowing the truck needed alot of minor stuff. Then occasionally on a complete stop as the truck came to a stop the brake pedal would get really hard. Now its almost at every stop the pedal gets hard, but not until I'm almost at complete stop. So far I've never lost my PS assist. I've done some searching here and found that there is also an accumulator which may be at fault. Some help on diagnosing which part may be the culprit would be appreciated.