One problem related to gas recirculation valve (egr valve) has been reported for the 2006 Mazda MAZDA6. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2006 Mazda MAZDA6 based on all problems reported for the 2006 MAZDA6.
There seems to be no one significant event that has lead up to the issues I am currently experiencing. The problem has gotten progressively worse with time over the last few months. It started with a minor stutter back in late July/early August. It worsened a few days after the computer was reflashed for the recall in early September. I'm not sure if that was a catalyst to this problem or not since it was stuttering before a little bit also. By late September the problem seemed to be worsening. By mid-October it was stuttering constantly when driving in stop and go traffic. The problem worsened with cool weather when the engine is cold. On nights below about 30 degrees, the car stutters and bucks severely for the first few minutes until the engine is warmed up. Acceleration is sometimes unpredictable during this time. So far, Mazda has replaced the mass air flow sensor and updated the ecu to the latest available as of November. Spark plugs were replaced prior to this per my request. Nothing seems to make an impact. It should also be noted that this problem (cold start) seems to worsen on rough/uneven roads. Gas type (93 or 94 and name brand) seems to make no noticeable impact.