Had the same sort of problem with mine. I could get a little boost if I was really easy on the "gas" peddle otherwise it would miss horridly with any kind of boost. Higher octane gas made no difference. Turned out to be cheap plug wires. I had gotten some with crimped ends in stead of proper ones that fit down onto the posts in the bottom of the distributor cap holes. Could be worn plugs also I guess. I also made a more direct ground from the intake manifold to the chassis (firewall). There's also a hard plastic tube across the valve cover that connects to the oil seperator(?). It often splits at that end and is hard to spot.