Turned out to be the glow plug, it had an os #8 in it so I went back to the F and that cured it, It also had been sitting around awhile so likely gummed up a bit too. put 3 more tanks through it yesterday between rain showers, then a mild prop strike dinged the tip , I likely could have sanded and balanced but the prop looks brittle so Its grounded until new one shows[:@] Went back to the cub today, they do fly a little different!!! keeps this newbie on his toes!!!