'97 LSS shuts off when using window switch.

[Tymcmedic]

I have a 1997 LSS automatic, which randomly shut off on me while sitting in a drive-through yesterday. After cranking repeatedly over the course of ten minutes it hesitantly started but revved and idled very rough. I was able to drive the mile home with significant decrease in accelerator response and power fluctuations, having to coast and sit at lights in neutral so I could rev to keep it from stalling. Also noted an inability to close windows as switches were not working. Some grayish smoke noted to be coming from the back of the engine compartment and from under the car once in park, but it was dusk and difficult to tell precisely where it was originating. I started it this morning without too much difficulty, but it hesitated and stalled without revving. After a few minutes it was able to run without revving, though not a smooth idle, so I popped to hood to look for the smoke, but I didn't see any. I got back in to try rolling up the windows which had been down all night, and as soon as I hit the switch the engine shut off. I started to car again and this time the windows came up about an inch before killing the engine. So the third time I tried brought the RPM to about 3500 and was able to roll up the windows, albeit with much hesitation and a major drop in RPM. Any idea what could be causing this?

[Tech II]

Remove the plastic sill from the bottom of the driver's door opening....now lift the carpet....if it is wet under the carpet, there are grounds under there that could be corroded....