Hi I recently ran my OS Speed 12XZ SpecII which I kept for months after I broke it in and tuned it.so when the first time I ran it again,the engine seems to have high idling and when I lower the idle,it dies.changed plug,checked engine(no damages internally),retune it but still same problem.only different this time is I'm using O'Donnell now instead of Byrons.guys please help.