Re: Chasing a sputtering gremlin!
I was having the same issues, all resolved by changing the module and coil at same time. Both are on Amazon Prime for $83 shipped. The $53 Amazon distributor is working great, once I changed the module to the ACDelco.
Re: E85 spark plugs?
Yes, it drives cold just fine. I'm running old fast system, so I look at lambda and tune on the gas scale. It idles around .95 and makes power around .85. Idles with 30 degrees and power with 20 degrees.
Re: E85 spark plugs?
Have the same combo with tr6 plugs, and it starts great. Orlando cold start is like 50F though. What afr and timing are you trying?