Crazy fuel gauge problem (long post)

Never seen anything like this before. 1970 Dart with standard dash. I replaced the fuel gauge because it would stick sometimes when coming up after first cranking. You could bump the dash and the gauge would unstick and go to the correct reading, so I knew it was a gauge and not sending unit problem. I replaced the gauge with one from Classic Industries that was made by Charger Specialties and replaced the voltage limiter with a solid state one from Real Time Engineering. I also replaced the circuit boards with ones from Year One. Now, the fuel gauge pulsates from empty to full in a rhythm(like a metronome). It's like the voltage is switching on and off. Any ideas and help will be appreciated.