ORIGINAL: H. Wayne S

There is nothing wrong with the MPI switches for ignition or anything else there designed for. Was the switch new? If so you were unfortunate and got a bad one, every manufacturer has one or two come out bad. Bad solder joint, piece of trash (plastic shaving or solder) in the switch. If it was not new, well there are a lots of reasons and things that could make it go bad.

Glad you found your problem. We had a member pull his hair out with a small intermittent glitch and tracked it down to an inboard wheel collar being loose and turning on the axle.
Never know what can cause that little Glitch Monster to come out.