I had a similar problem with my '47 F**D. I thought it was the ignition switch also, so I installed a new one. Things worked good for a few months then the gremlin showed up again. It ended up being a bad wire connector that connected to the back of the ignition switch. The crip looked good but I think that things would wiggle and then the wire would go open causing the car to buck, stumble ect. The car has the original steel wire, not copper. I ended up putting all new ends on each wire and have been driving it without trouble for 2 months now. Just something I learned after about pulling out every hair on top of my head.
