I had an 89 Winnebago Warrior with P30 chassis. Bought it in 2012 with 82K miles. Ran great but the brakes were terrible, like scary terrible! After trying everything else possible, new fluid, bleeding the hydrobooster, etc. Finally had to bite the bullet and replace the Hydroboost unit. Voila! Problem finally solved. Considering the age of yours you may be headed for another hydroboost also. Autozone had them for less than $150 in 2013 (rebuilt) but worked great! Good Luck!
2010 Fleetwood Bounder 35H Workhorse
Prev: 2001 Damon Intruder (Model 351) V-10 Ford
"The older I get, the better I was!!