Quick update...
Let me begin by saying that Qmulus and 78F350 were completely awesome in getting me a new immobilizer. The shipping and turnaround times were incredibly fast and the prices were stupid cheap. Thanks guys, I owe you big. Also many thanks to BirdDog and Particlewave who took time to help with great write-ups both here and through PMs.
But... rebuilt immobilizer was installed and the exact same symptoms persisted. No change for better or for worse, so apparently the immobilizer wasn't the problem. Next guess, the ignition switch? Why would it go bad after it rained? It's mounted high and dry. Is it possible that humidity inside the car finally did the switch in? Or is it just a big coincidence that it happened right when it rained?
I had ordered a pair or switches but they turned out to be the wrong ones (
Meyle 4A0905849BMY Ignition Switch. Though they plug in the body is taller and the key/switch position is different. Turns out there are two versions. If someone can direct me to the right version it would be appreciated ('99 Boxster base)
I also opened up the OEM ignition switch to see if I find anything unusual. Looked pretty decent inside. It's also a very simple mechanism and makes me wonder why they go bad so often. I gave it a good cleaning with electrical cleaner spray, especially the contacts, and put it back together. No luck
So I guess now I just have to wait for the right switch to get here and pray. In the meantime if anyone has any more suggestions I'm all ears,