My 2000 F250 appears to have a problem with the brake. Sometimes it seems to be very hard to push in and does not brake well as though it is not power assisted. But then after a few pumps on the brake pedal it acts normal. I check fluid level and it is ok.

What should I look into?

 

When was the last time you flushed your brake fluid and inspected your brake lines?

Stewart

 

And have you checked power steering fluid level. It takes tranny fluid not power steering fluid

 

sounds like your brake booster is failing. how does the steering wheel feel? definitely figure it out before driving anymore. a wreck would suck.