[Stophos]

I have a problem with my 88 930 that I thought I had narrowed down to my brake booster but I am having second thoughts. The problem is that after even a very short ride all four brakes do not fully release. Initially I thought master cylinder and replaced it. No difference. Then the hoses, then rebuilt the calipers. I rebuilt the peddle set thinking it was sticking. No help. I took it for a ride pulled it on the lift and the brakes were locked up so I disconnected the booster rod from the peddle set thinking this would eliminate a mis-adjusted rod. No difference. I removed the booster assuming it to be the problem but I am thinking I am missing something. I removed the master cylinder from the booster and could hear pressure releasing which I think is normal. Visually it looks good and the piston moves freely. Before i purchase a booster can Anyone tell me what I may be missing?

Thanks - Chris