Nissan Repair: 1995 maxima engine idle shuts down to 0 when I wait at the signal, throttle position sensor, air control valve

Question
I have a 1995 maxima GLE. Lately, when I stop at the signal lights, sometimes[not always] the idle slowly goes down to 0 and engine shuts down and all the dashboard lights come up. When I try to restart, it restarts. Sometimes, same problem happens consecutively when I'm trying to restart the engine. After restarting, I press the gas padle little high[RPM 3 or so] thinking in case engine has any water[or gasoline has water for that matter] in it. This problem started today[April 7.08] and already happend several times through out the day.
Please note, this car had engine check light came on about 8 months ago. I checked the code; it said 2 problems as code diagnostic. One: "knock sensor" and two:"EGR valve high/low pressure". I did extensive research online on those two problems and tried to clean up EGR myself and put it back on. But being the EGR in an extremely awkward place in that car made it impossible for me to do the job. So I left  that problem as it is. Car didn't didn't give any functional problem thus far until just today the problem I just described above.
Please help. What should I do?

Answer
Viv,

I would replace both the knock sensor and the EGR valve.  Both could cause your problem.  Second, if the problem still persists I would look at cleaning the throttle body and check both the throttle position sensor and the idle air control valve.  My bet would be the idle air control valve if the knock sensor replacement along with the EGR replacement does not correct the stalling problem.  But, these both need to be replaced regardless.  The knock sensor needs to be replaced since it could allow the engine to knock and that would cause engine damage.  The EGR not working will cause sluggish response, bad idle adn poor mileage.