91 accord, when clutch is engaged the idle is ok, but if I press the brake at the same time the idle goes up and down. thanks for any help

 

I had a similiar issue with my 96 auto, it was revving in park but not in drive, turned out to be a leaking intake manifold gasket, check for vacuum leaks with a spray bottle of water, you should hear a decrease in rpm when the spot with the vacuum leak is sprayed, don't go crazy with the water though, just a mist will do, hope this helps