too rich not too cold & the excessive richness might (& very likely) might have been from too much pumping/choke/float setting/needle/seat leaking as opposed to it being jetted too rich but I dont know the OE 750 jetting (if it's rich or lean) or what you have in there now so I am just thinking out loud. There have been some comprehensive plug threads in the past with the gist of em being the cheap offshore materials/stuff being outsourced causing problems. I'd glassbead your Autolite 85's (some ain't OK with that, I am) & toss em back in (or a new set if preferred) & you'll be fine.