I've just been through the dropping onto one cylinder experience on a particularly wet ride. Number 3 and 4 coil sticks on my bike showed corrosion half way up the metal sleeves,with,strangely,number 1 and 4 spark plugs showing a lot of corrosion around the hex head on each of them,2 and 3 were like new. I took them to a friend to seek his opinion and he tested them whilst I was there,unfortunately I can't give give you any figures other than to say all 4 were the same.
I thought I'd replace all the coil sticks and found that RMSTATOR-EUROPE had an aftermarket replacement at a very reasonable price with rather unreasonable freight costs. In the interim I thought I'd remove the metal sleeves,clean any corrosion,throw in some new plugs and give it a ride. In a word,PERFECT.
Admittedly,I never had any of your symptoms,so I assume my problems were water based. I'd be inclined to get them tested,replace any defective parts,new plugs and give it a crack. If like mine,and many others,you have corrosion on the sleeves,you can simply remove those sleeves and see how it goes,if it doesn't work,then replace them.