You are suffering from patrolium contamination. ya right? whats that? it means at some point someone accidentally put some kind of patrolium based product in your brake master cylinder which then infected the rest of your system destroying anything made of rubber. You see ordinary brake fluid has a really high boiling point depending on the grade (dot3 dot4and so on) when it's contamindated with regular oil or accidentally with power steering fluid (most common) it allows your fluid to boil at la lower temp increasing system pressure and then slowly applying your brakes, until it cools down releases pressure and allows you to drive again.

how much oil? less than a teaspoon can cause all your seals to double in size in 4 hrs. The oil stays soaked in the system (I.E. ANYTHING RUBBER) so if you just flush it. your new fluid will be recontaminated and you will still experience the same problem. the only solution it to replace all components that contain rubber! and flush all metal lines with a fast evaporating solvent to ensure they dry quickly then after installing all new parts flush with clean fluid. super expensive.

sincerely 10yr acura tech. have only seen this once and it was on a chevy.