Thanks Steve. yes it was only happening under heavy load. The good news is I fix the problem. First I changed the spark plugs and wires. When I was putting the wires back on I followed the books lay out and my car wouldn't start so I pulled the #1 plug, took the cap off and cranked the motor over until it was on the compression stroke put the cap back on with the #1 plug wire where the rotor was pointing. It started right up and no more miss even doing 100 mph up hill.