Inherited a 1979 that had been sitting for 9 years. It had a half tank of fuel. Refueled with premium fuel and drove it for 240 miles. Stopped and refueled it with premium fuel (18 gals). Got back on the highway and it started to sputter and stopped. Could not keep the engine running. It will start and run for a minute but then dies. Rebuilt the carburetor, replaced the fuel filter, fuel pump. Still will not run. What next?