Hey Guys I have a Maxx II and it has an 18 hp Vanguard and is running weird! one day it runs fine the next time it starts up perfect and will idle but when i take of it starts sputtering and then only runs with the choke on. i have replaced the fuel pump, sparkplugs, fuel filter, fuel line, cleanded tank, air filter, cleaned the carb-total brake down and rebuild. i did notice when it does start up and run good and i 360 spin it boggs down usually only one way though. So i am at my wits end and i want to get a new motor for it but i do not know wich motor ? can i go up in HP there are so many vanguards do i want the oil cooler model. any help would be great.