My brakes messed up on my 88 pickup the other day all the sudden one go to the floor board then be fine then a few minutes later they'd go to the floor again wanting to do some upgrades on the booster and master cyl wandering if there are any good ideas let me know if so!

 

Ideas if pumping the brakes helps build up pressure it's most likely the master cylinder. They commonly go. Other things to look for. Is your brake fluid topped up? ( fill it ) Is the fluid level dropping? ( there is a leak ) Is your vehicle equipped with drum brakes? If so, is the brake cylinder leaking? ( fluid on inside of rear wheels( replace cylinder)) Are the brake lines leaking.. ( replace lines ) hope this helps some.