I have been working on cars since about 1970 and in the past never gave any thought to fully flushing a brake system. After acquiring my 2003 RAM 2500 in 2018 I realized the brake fluid was dark and probably needing flushing. Only recently did I finally purchase a decent pressure bleeder system and adapters to assist me in doing a good job.
I did my 2004 car for practice and then the RAM knowing it needed brakes and I didn't want to contaminate new calipers and hoses with old fluid.
The first flush of the RAM was some really nasty fluid. The brakes worked noticeably better after that, and of course really good after installing new calipers, pads, rotors and hoses and doing a second flush and bleed.
It appears that the '93 F53 chassis was equipped with a Hydroboost power booster rather than a vacuum booster. Hydroboosters rarely fail but you want to keep fresh, clean power steering fluid in the system also, and the booster or power steering system could also be giving trouble.
Given the age of the motor home, I would consider all new hoses (old ones can balloon under pressure, causing weak brakes) and a complete flush of the system.
Charles