On Friday, I came to discover that one of my truck's spark plugs was disconnected and, likely, had been for the three months that I've owned the thing. I reconnected the spark plug and it's been running smoother and without the backfiring that I'd grown accustomed to. Needless to say, adding another cylinder is going to change the fuel consumption characteristics of my truck so now I've got two independent variables contributing to my mileage, which will change the way my science works. I will figure out a way to account for this and get back to you eventually when I figure out what, if anything, the acetone does.
What surprises me most is that I'd been driving the truck for about 3 months and the disconnected spark plug had gone completely unnoticed by me.