I dont know what is wrong, star normal than going down and than off??? Carb is in fault but whereeeee? http://www.youtube.com/watch?v=pKFMHVR6-Cw&feature=youtu.be
as i said, check each and every thing in the faq, from top to bottom. it could be you have a number of faults and some chump has messed with all the linkages to work around the problem. if so you wont be able to diagnose it so simply. so check everything as per the faq, fix all the problems then see where it leaves you. if its not runnign right after that check my sig and read the haynes2e2manual.pdf, this has more advanced info on resetting all the internal linkages