Valve adjustment may help your compression and injector cleaner may help your injectors. A hot compression test after you check valve clearances will tell you if the problem will go away easily or not.

Periodic oil tests may tell you if your engine likes the single tank life or not.

If there is PHO or fat in your oil, RUG, D2 or other solvents may promote it's settling down onto your tank strainer.

You might just pull the supply & return lines & stick them in a jar of D2, see if it starts better.

As for peoples results in cold weather, they can vary as widely as the fuel used. Someone may have good results w/ neat canola, you may have butter. If you drain your fuel return line into an olive jar and put it on your dash, that will tell you what the fuel is like, more or less every morning (thanks chris goodwin). Wont tell you much about the strainer, or what won't make it past the strainer.