I have a 318 with a Onan p218 engine that has just started running rough (hunting). However, it runs fine when mowing. Last week it was fine, this week it started hunting. I thought it was the governor but after about 10 min. of mowing the battery light comes on. I'm starting to think it's an electrical problem. It has new plugs, new gas filter and Ive put Seafoam through it with no change. I'm OK with mechanical problems, but I get lost when it's electrical. Any suggestions?