Welcome to the site Bill!
How long have you had your BD? Did the problem just start? How mechanically inclined are you?
As for the EHC, it gets blamed for everything and usually get sent back to the factory and test positive. The are threads on here from "Gas Man" and myself on going through the wiring and making sure every connection is tight and no wire have backed out of the little connectors. Then fill them with dielectric grease and you can even shrink wrap and seal the ends with RTV. There are a lot of connectors so this will take a while but seems to end any electrical issues. And be careful washing your bike, they don't like to much water so just spray and wipe it.
Do you have a manual. If so then go to the page that show the error codes on the EHC. Turn on your key and see if any red lights are lit up. If so then you have a ground somewhere and are going to have to do what I explained above. As for the tach I would say that if the wiring doesn't cure the problem then you need a new tach board and you can call Vicki for that. She will get you the best price. Just be aware that the tach lights flash wildly when the RPM is set below 950. You didn't state when the lights are flashing. If the lights go away when you rev the motor then the idle is set to low.
Fouled plugs in 5 minutes! I bet you are using the enricher device. Don't use this device ever unless it's real cold out
then only to start the motor and then turn it off and keep the motor running with the throttle. The enricher will foul your plugs real quick. It's not a choke, it dumps raw fuel down the manifold so don't use it!!!
You're jets are good size so I would think your problem is fouled plugs from using the enricher. But, if not then have you checked for leaks around the intakes and exhaust? This will cause your popping and spitting but usually causes a lean condition not rich. I think you're using you enricher to much and then trying to run it with fouled plugs and it probably sounds like it running on one cylinder.
So, replace the plugs, check that your plug wires are on tight at the plug and coil. Start the motor without the enricher and set your RPM to 1000 or above and call me in the morning!!
Did I mention "Don't use the enricher"!
later,
Ray