1996 Chevy Monte Carlo Rough Idle, Stalling When it warms u

As a fan of this website. I have scoured the forum for an answer to my problem. The car starts fine but when it gets up to operating temp it starts to rough idle and want to stall. I noticed this to be more obvious when stepping on the brake (in park or drive) or when I turn the lights on. I have replaced wires, plugs, sensors etc. Coils have been tested, filters changed, charging system is charging. What else could it be. No codes set either and the mil works. What could this be? Has me stumped and I think others with this problem are baffled too.