I have a 96 maxima se automatic. when I am at a stop light with the transmission in drive with my foot on the brake my car will sort of make a shutter every once in a while. I can feel it vibrate through the brake pedel and the engine drags down for just a sec. Sometimes it won't do this at all and other times it will do it like every 5 seconds. it only happens in drive with my foot on the brake. WHAT IS WRONG? I just replaced the knock sensor, plugs, air filter, fuel filter, pcv, and cleaned the throttle body. HELP!

 

Clean IACV.