I joined this forum to attempt to solve this problem. I have a 07 Mazda 3 i 2.0 . I have a rough idle when I am stopped at a light. The biggest problem is my car is not throwing a code. It was also giving off a sulfur smell until I replaced the purge valve, but the idle is still there. I have also replaced the air filter and cleaned the MAF the idle still exists. Also when my foot is on the gas just slightly i can hear a slight whine from the right side of the car, when the throttle is fully open it goes away. Very rarely will it choke while I am driving or accelerating.

The next thoughts are egr, bad motor mount, or oxygen sensor.

Any help would be appreciated.

 

I have the same exact problem, same year same everything, I am really clueless but don't know if there is a relationship we had our firmware updated on the car due to stalling, the stalling is know gone but shortly after the card developed the same issue as yours. I have been closely monitoring the car and I noticed that when at a stop the RPM's actually drop below 500 should be at least 700rpm and that is when the issue begins, i feel that is a case for the dealership to look at, just wanted t add some input since it appears to me many people are having this issue.