I sorta am at the same point. I want to fire my engine soooo bad, but no wiring.
So my plan (waiting on weather and some money) is to paint the inside of the cab, door jams, windshield, the outside of the cab between the cab and bed. The assemble everything, do the new wiring, assemble the interior, fire the engine, the eventually paint the entire outside. I felt this way it would get a bunch of stuff off the floor and prevent me from having to disassemble a bunch of stuff for later stuff. It really can be a pain and yeah I am like you I worry that sometimes I am in a slump and losing interest. Especially with me right now as it seems all I am doing is sanding/blocking and I see no difference in what the truck looks like.
Keep hitting it. I am enjoying reading, although I don't get to sit down every day like I use to to really read board posts. This thing called work seems to interfere.