thanks for all input so far. To address replies:

-I don't know how to check injection timing. Hot link to instructions?
-re WVO, same car running same blend started much easier a few years ago. Also, my 300d started and drove great at 30f this AM running same blend. Been running wvo for 8 years and familiar with cold weather behavior. HardER starts? Sure. Hard to start period? Not normal.
-re marvel mystery oil, how to do it? Pull injectors back out and fill through injector hole til full? Since this will eventually seep by rings into crankcase oil, should I plan on changing oil after trying this treatment?

Again, thanks all for your time and opinion!

Best,
Brad