i sometimes have a similar thing happen to me. i have a the GT1 and sometimes when i start it up it studders and it has even chugged right on off. that all happens before i even get it in to gear. someone suggested to me to replace the fuel filter, but i haven't had the chance to change it so i'm not sure if it will work. something to note is that fuel filters are often not included in general tuneups and isn't in the warranty either.