I am looking for HELP my 69 Mach a 428 car is giving me a fit with Vapor Lock.  In slow driving, stop and go traffic and at drive away after a stop of 15 to 30 min. I have changed the pump, and wrapped the fuel line pump to carb and installed a 3/8" thick carb gasket with NO improvement.  

One suggestion - pull the intake (if the 428 has a stock iron intake, best get a hoist LOL) and block the exhaust crossovers.  If it's an aluminum intake, especially do that.  If it has a stock Ford aluminum spacer under the carb, replace it with a Moroso 4 hole plastic model with a metal heat shield under it.If you're not up to pulling the intake, you'll need at least a heat shield - preferably under the spacer.  You may have to modify the shield for PCV operation.

If you don't drive the car much, you might just have a problem with the fuel - the specifications change with the seasons.  Google on "gasoline Reid Vapor Pressure".