The brake pedal on my '99 Boxster doesn't immediately return after applying the brakes--after a second or 2 the brakes release and the pedal returns to normal. Any ideas?

 

you could check the pedal linkage but it sounds like the booster if all the brakes release

 

Now it's gotten to the point where the brakes don't release without a foot under the pedal to raise the pedal back to normal height. Would this have anything to do with the "vacuum brake line"?--this was replaced 2200 miles ago.

 

what is the brake repair history on this car...in detail please...it may help in advise

 

Brake repair history: 9/30/2010 3111 miles ago---4 rotors + pads. 12/28/10 2177 miles ago vacuum brake line replaced--this was done at the same time as an IMS retrofit, tiptronic trans exchange,rms seal, oil separator--no brake problem was reported at this time--shop decided to replace the vacuum brake line because it appeared to be near the end of life.
The problem seemed to get worse after I had the brake system flushed a few days ago as part of a 4 tire replacement. I had the brakes flushed after I noticed that the brake replacement job back in 2010 didn't list any brake fluid charge on the list of materials used.
I would take it back to the shop that did the 2 previous repairs but I now live 625 miles away. Eventually I guess I'll have to trailer it to Reno--2hours away--I believe this is the nearest place with either a dealer or indy shops. The car also needs a rear alignment (the tire shop that replaced the tires & flushed the brakes couldn't do it). Rear alignment necessary because 2 new Pirelli PZero Nero's wore out after only 2600 miles--the right more than the left (the car was aligned , or I paid for an alignment at least, 500 miles before).

 

with this additional info i would check the master cylinder first then the booster. imo. they did use the right fluid ?

 

Check for major air bubbles in the brake system.

 

I would certainly have it inspected instead of talking about it here. You have a vehicle that's 13 years old and has had brake work done. Something wasn't done or done correctly so I would get it fixed before you drive it any more.