Short story: Fixed!
Long story: Tried a bunch of experiments to corner the problem but couldn’t find anything. Received a lot of insightful comments from the guys on K20.org, and a common theme was that many had made the exact same goof I’d made, accidentally swapping the MAP and throttle position connectors. Anyhow, the other car owners said that quite often the MAP sensor gets fried and needs to be replaced. (I went back and checked the schematics, and somewhat unbelievably, Honda wired the two identical connectors opposite, so that if you ever accidentally swapped them, the MAP sensor would be powered with reversed polarity. What were they thinking, especially with both sensors so close together.) Anyway, what threw me off was that the sensor appeared to work so I didn’t really consider it as failed. However, enough people said they had the problem, and being that I still couldn’t get it running, I figured there was nothing to lose.
Since my car is turbocharged I had installed a non-stock MAP sensor – one capable of reading higher boost than the stock part. Because of that I don’t have a spare, but do have the original factory sensor. Because KPro is so easy to use it was just a matter of telling it that I had put the stock unit back in and it handled the rescaling. The first hint of success was that instead of reading -28″ MAP during ignition-on (which in hindsight should have tipped me off immediately) it read ~0″. Sure enough, once started it settled into a nice smooth idle.
The only downside was figuring it out so late in the day – as my curiosity of whether it could be that simple of a fix demanded coming back out to the garage in my PJs. So while my PJs now reek of exhaust I’m very happy. The bummer was not getting the test drive in, but that’ll happen soon enough, but this is a huge load off my mind.
Oh, and I still smell gas but can’t figure out where it’s coming from. It’s as if there’s an open cup of fuel hiding in the garage – every once in a while I get a good whiff of it. However, after going over every inch of the fuel tank and every connection in the fuel lines, it’s still a mystery, as nothing showed up with the “wipe test.” It’s always something.