The good news is that I'm now 100% certain that when I put this multi-pin connector back together, I did it incorrectly, which hopefully explains my car's symptoms. I realized what I did two years ago when I took this thing apart. Instead of simply prying apart the two halves of this connector by wedging a screwdriver between the two halves and gently twisting, something compelled me to remove the caps that hold the wires in. So, the wires did what God and Porsche never intended - they popped out.
And that's the bad news - I haven't been able to figure out how to put the wires, specifically the ones facing the firewall, with the female connectors, back into their sockets in the black plastic receptor (not sure exactly what this piece is called - I have a picture of it below).
After spending over an hour studying the wiring diagrams (thanks to Eric for pointing out where on the diagrams this connector is located) and banditsc's pictures, I'm now 100% confident as to which wire goes to which socket in the two halves of the connector. I didn't have too much trouble putting the wires with the male bullet connectors back into their half of the connector, as this is the half that goes into the DME, and thus is relatively accessible, especially with no passenger seat. The other half, on the other hand, is a nightmare. It's stuffed way back under the dash, making it hard to reach. But the worst part of it is that there are so many wires (11 total) that they all get in each others' way, making it very hard to maneuver their connectors into their sockets in the plastic connector. But the real icing on the cake is that the connectors don't fit very snugly into their sockets in the receptor, so once I get a connector seated, it pops out as I maneuver the next one into place, like a twisted game of whack-a-mole.
Here's a picture of the nightmare I'm dealing with:
Yes, I have to somehow maneuver that jumble of wires into that black receptor I'm holding in my left hand. I need a team of six-inch tall people. Once the female connectors are in place in the receptor, the cap will hold them snugly in place, so I should be able to easily push the other half of the connector, the one with the male connectors that I've already placed in their receptor, into the female connectors, and everything will stay together. It's getting to that point that's the challenge. I did it when I first put the engine back in the car this past April, so obviously it's possible, but I do remember it being excruciatingly difficult, and obviously very easy (at least for me) to mess up.
I need a brainstorm to figure out how to get the connectors into their correct slots, and to stay put as I put the remaining connectors in. I may have to fabricate some sort of holding device, but I'm not quite sure what form it would even take yet. Or figure out some way to make the connectors stick when I put them in the receptor. Or figure out how to move this whole mess onto my work bench. Any and all ideas are welcome. Thanks.