2007 gs350 . 5 days ago while driving I stopped at a stop sign engine stalled ,check engine light came on ,and was running rough . Checked code ,was p0301 ,cyl 1 misfire . Checked cyl 1 spark plug [ original iridium ] ,noted a piece of porcelain broke off at electrode . Replaced all 6 with ruthenium plugs . Ran fine . 2 days later after driving to car for while when I tried to start it won't start after several tries . I let it set for about 5 minutes it started fine and has been last 2 days . Showed no dtc on dash . Checked code on reader and showed a logged code p0301 which I hadn,t cleared from before . Is cleared now . Is changing to a different type of plug such a issue .

 

The plugs that you replaced with were they original oem or denso? The denso originals cost $13 per spark plug. There are many knock off denso plugs and fake oem plugs on amazon and ebay. If you didnt purchase original plugs then I would replace them and mae sure to buy the plugs from a reputable seller.

The part numbers are FK20HBR11 and Denso 3473