Red, Do You Think The Problem Occurs After Rain, Melting Snow, Or A Car Wash ?
See if this sounds like a possibility.
Mazda issued a TSB (technical service bulletin) for 2006 - 2007 Mazda 5 vehicles to help their technicians diagnose intermittent misfire (idle fluctuation/engine vibration). They have found that on some of these cars it’s caused by water settling around the #1 spark plug after it rains or a car wash.
First this condition must be verified by a technician to be sure that is the problem.
Three page TSB # 01-023/07 outlines a fix, including removing the w/wipers, some cowl parts, cowl grille, and weatherstrip. Then 3 new “pads” are installed together with a new “modified” ignition coil (only for #1 cylinder). The bulletin has diagrams and instructions and gives the part numbers of the 4 parts needed.
Mazda was performing this repair under warranty for cars that were still covered.
CSA