I have a Gravely ZT HD 52 with Kawasaki FR691V. I filled tank quickly & over filled it with a bunch of spillage. The gas went down & air bubbled up as it did. I started the engine & white smoke poured out for about 6-7 seconds. I went ahead and mowed and had some sputtering or more like burps here and there at 1/4 throttle and it dies when set any lower. If throttle is all the way up it seems fine. Any ideas on what this could be? Appreciate any suggestions.