I have the same problem with my '99 sno pro just not as bad. I have found that it is from a rich mixture not lean. some times it will not go off the line if you back off and roll on the throtle it will go. this only happens if i let it idle. so i don't let it idle. it doesn't happen as much when it is colder (around 0 degrees F) if you run in warmer conditions this might be the problem. If you think it is lean then i would check your jetting and oil pump settings. I run 310 main jets in mine which is plenty rich for me good to -10 F. I would also check the power valves. make sure they are clean and move freely. The updates will do nothing for performance unless one is broke (there would be a big difference then). If possible I would try to check with the previous owner to see if they were updated just so you know. mine also had worn clutch weight bushings which made it shift slow. red oil that had a sweet smell was probably Klotz techniplate. this is a good oil but so is Amsoil I run amsoil. the previous owner if experienced could have adjusted the oil pump to the different oil flow. also make sure your plugs are BR10eya's unless you run it slow alot. but then you shouldn't have got a sno pro. you can also do a compression check it should be around 120psi. also check that your timing adjuster is on 0 or less unless you run raceing gas. and i would keep it on the cold setting. this all I can think of. So I would first check jetting, the oil pump and the power valves.