I noticed a burned plastic smell on occasion about 10 trips ago. Didn't realize it was the flush out plug until the other day. The motor performs as always, but there is a different sound to it (the exhaust note is a bit raspy). It cranks a while before it starts now sometimes as well, when it never did. I don't think it's overheating since the temp light has not come on as it has in the past. Could it be an exhaust leak?? Fiberglass is burnt a little bit also on the cowl cover in the same area as the plug.