Backwing,

Yes, the 108's do take a couple extra seconds to "idle down", as Montague stated. The one I had about a year ago also had a problem with the head bolts loosening. Give them a check also, and re-torque if necessary. This could also be part of the problem.

They are a little temperamental until you get a couple gallons through it. In fact, my Son-n-Law has mine now and it can still act up now and then!

I wouldn't mess with, or change the way you have the motor mounted...horizontally should be fine.

Best of luck to ya!

Gary