i bought it used, had the following work done, new radiator, wather pump, thermostat, hoses, carburetor rebuild, major tune up. runs fine on freeway, BUT! any small up hill grade when you open 4 barrel carb, the engine heats up and exhaust manifold turn cherry red!! Vacum is higher than normal. back pressure ok. 2 1/2 tail pipe. new catalytic converter and muffler. HELP!!!!!!!!!!!!!!! got any answers???????????????????????????????????/