I was in graduate school at the time and supporting us by playing in a rock 'n' roll band. One night, after trying unsuccessfully to put Eric back to sleep, my choices were to go stark raving mad or write a song. So, because it's against the rules for a psychologist to go crazy, I wrote a song titled “Three O'Clock in the Morning Rockin' My Baby Blues.”
It was pretty good, actually — a heavy blues number. I started adding verses to it during those early morning rock-a-thons. When Eric finally began sleeping the night, the song was 10 pages long, typed, single-spaced.
It is not at all unusual for a child's sleep pattern to change around the 3rd birthday. Some children outgrow the need to nap around this time. The fact that your son is on-again, off-again with his afternoon nap tells me he's going through this transition.
In that event, I encourage you to stop trying to fight city hall. Dispense with the afternoon nap altogether. Put him to bed at 7. Cut his bedroom door in half, just above the knob, then re-hang it and turn the knob around so you can control the lock.
After you put him to bed, close the half-door and lock it. Children don't like being closed behind a full door because they can't see out, but they accept the locked half-door fairly readily. Acceptance usually takes about a week.
A second, slightly more painful option is to dispense with his nap, put him to bed at 7, and just wait this out. As I said, it's probably a transition that will resolve itself by the time he's in high school. But seriously, can you put up with this for a month or so?
Option 3 is to put both boys to bed in the same bedroom, at the same time. Close their door and let them play themselves to sleep. Tell them that as long as they're quiet and don't come out, they can keep the light on. If they make noise or come out, the lights go out and they have to go to sleep.
If you enforce that calmly, you should be over the hump in a week or so, and you can return from the living dead. I am living proof.