WD, I don't think the air filter would be clogged that badly, but I would replace it anyway ($5?!). You might want to go through the carb though. It seems a little rich (black plugs). Fuel sitting in the float bowls is no good for the power valves or accelerator pump diaphrams (it will deteriorate them leading to holes). Fuel will leak into the manifold through the power valves and onto the manifold through the accel diaphrams. This is true for Holleys. If the valves are black too(looking into the exh ports), It is running too rich. They should be a light tan color. My thoughts........Mike