Why might a 1992 Olds Cutlass Supreme not idle right and die when you put your foot on the brake?

check your fuel presure regulator Might be as simple as a fuel filter. Or could be many many things. Good to start with this and vacuum and potential bad sensors like EGR or MAP sensor. If your fuel pump (inside the gas tank) has been changed recently, then that is ruled out. I had the same problem. It was tested as being the Map sensor. The pistons were firing out of time and the engine ended up running rich. The catalytic converter ended up becoming clogging and turning cherry red because of the rich mixture. I also had a 1992 Olds Cutlass Supreme. I have the same problem with my 91 olds, its in the IAC motor, take it out and clean it.