I'm at a bit of a loss and need some advice, I have a 216 in-line six in my '50 Chevy. It runs beautifully at lower speeds around town, but when I get it going on the highway, really give it gas, after about a mile down the road, it starts to stumble and then dies. It sounds almost like a small plane coming in for a landing. The fuel pump has been replaced, the carburetor has been rebuilt, the coil has been replaced, Spark plugs are new, distributor looks like it's in good shape, does anyone have advice that may help narrow the problem down? Or point me to a thread that might help me out?