coil or igniter?? help!!
 

My 74 RX-3 has an 85 electronic ignition, the problem is that at idle the rpm gauge bounces between 1.5K to about 2.3K. When the engine is running it stays steady. I changed the wire to the leading coil and it stays steady, only does it with the trailing coil. What can be causing this? Any ideas/sugestions?? TIA, Dave