Try running a blend of VP C-12 108 octane racing fuel with 93 oct. pump fuel. I run this in my '69 4.1L OHC6 250 Sprint, 10.5:1 comp. ratio, and it makes all the difference in the world. It woke this 6 banger up! Vp fuel is actually good for your engine..it's pure hydrocarbon fuel which tends to clean while producing a better burn giving you better response, no clatter or stumble. I usually mix it half and half, sometimes straight, when I can afford it. It runs about $4.35 per gallon. Check it out sometime!