New 20 ounce tumblers available now! Forum donation credit with purchase. https://www.wildguzzi.com/Products/products.htm#Tumbler
Coil kill switch could be flaking out on you....Mark
Unplug the tach. See if it runs better. Also check the ignition switch and wiring. Hunter
Smells like rotten condenser You tested another one . Was it the same ? Coming from the same place ? Nothing wroten on them ? For information ,we faced a batch of very unreliable condensers , sometimes not working from new .
You beat me to it - I've had some very strange problems occur but disappear when I dropped in a new condenser.