1987 Yamaha ProV 150 had developed a miss at idle speeds and it has gotten worse to the point where when it misses it dies out about half the time. Speed the RPMs up just a bit and the miss is gone. Only there at slowest idle speed. I have changed the plugs and this didn't really help. Any ideas what could be causing this? Can you change plug wires like you can on a car? Do they just pop out of the little black box thingy (technical term alert!--assuming this is a coil of some sort) they come from. I tried and they didn't just pop off and I didn't want to mess anythign up by pulling too hard. The wires all look good from the outside. Is it possible one of the coils(?) is bad? How do you determine which one if this is the case?