do you pull out the break in shim? The 8MM restrictor is too large. Go to 6.5 what fuel are you running? Lower your Throttle EPA to 70%..anything more than that is just wasted power and fuel. also, check your idle. The idle gap should be just a tic opened. somewhere around .3-.4 MM. Use a colder plug like P4 or P5 and then tune around your idle and plug. You would be amazed what happens when its all set up properly..PS. These methods work with all engines.