You know what. Upon looking at my recorded clips when it was running just fine, I stopped to fuel it up with something called "Miles 95". The description (a rough quick translation from google translate to save time) follows:
"In our 95 miles gasoline we put a gasoline additive containing a friction modifier. Tests show that regular use of 95 miles gasoline can provide up to 2.7% * lower fuel consumption compared with a 95 octane gasoline with the standard addition to Swedish law requires."
I did notice that after about a mile, the problem started to occur. I did have my doubts when I was putting the gasoline in but thought "meh, it's octane 95".
Would it hurt to go and fuel up with the real usual gasoline? I realize that I should still probably check most things suggested here since the previous owner didn't take proper care of it, other than riding calmly for a 77 year old.