os 120 surpass pumped engine
 

please help me,i have a 120 pumped surpass [i think it is the first one made back in the early 90's]not a surpass-ll or a surpass lll,any way i can not know matter what i do get this engine to have any kind of smooth transition from idle to wide open, no matter how much or less i turn the needle valve it doesn't help, it get especially worse it seems as the engine warms up,i have tried to turn the big flat screw right in the back of the pump and it still doesn't help it,also the engine seems to run worse when mounted upside down in my Sig 3-d mayhem i have no instruction manual for this engine, so i don't know what to do,the engine is still in great condition has tons of compression and everything is very clean,it also idles great, any help you guys can give me would be appreciate SO much , thanks