While stopped at a light the brake pedal goes down a little sometimes Checked for air in the brakes and brake fluid what else could it be?

First of all, how did you check for air in the brakes ? I've been working on my brakes all day and haven't come across any sort of way to check for that. If you suspect there's air in the system, then the appropriate reaction seems to be bleeding the brakes. Secondly, just because there's fluid at the right level doesn't mean it's the *right* fluid. Brake fluid absorbs water directly and can intake air through small pinholes in lights that may not be visible. Both of these will affect the performance of the brake fluid - and thus the brakes - because both water and air are highly compressible whereas hydraulic fluid shouldn't be. Therefore, just having the right amount of brake fluid in there doesn't really matter that much if it's full of junk. When I bled my brakes today the fluid going in was crystal clear, and the fluid going out was dark brown like used oil; ugh. I suggest bleeding one of the wheels and bit and seeing what the fluid coming out looks like. If it's not new looking, or it's been 2 years or more since you've bled the brakes and fed new fluid through I'd consider bleeding the entire system. There are lots of articles to teach you how to bleed the brakes. Here's one thing NONE of them mention: the bleeder valves often get rusted in. What should have been a one and a half hour job for me turned into an all damned day affair because I messed around with vise grips, torches, wd40 and all sorts of effort to get the bleeders to loosen. In the end I just bought new calipers. They cost a mere 20 bucks each, and I did both sides of the front at the same time. Chances are you can mess with a stuck bleeder valve as long as you want and still end up needing new calipers, so if you have an older car, or the bleeder valves give you the least bit of fuss I'd consider new calipers right off the bat.