I have a 1993 del sol si. Recently when i hold the brakes at a stop, the pedal will slowly sink to the floor. It brakes fine, and even when on the floor it stays in place, even when i rev while holding the pedal down. It starts off feeling normal and only sinks after ive held the pedal down for a few seconds. The fluid level is fine, too. Any thoughts?

 

your master cylinder needs to be replaced

 

like he said

 

check for leaks around master cylinder, brake lines.. etc.. or just replace the MASTER CYLINDER

 

yep, MC is bypassing.