Engine Performance problem
2006 Pontiac Torrent 6 cyl Two Wheel Drive Automatic 41,000 miles

When I go to a drive through car wash or it rains very hard, my vehicle has problems. Not only does water leak into the overhead lights inside, but onto the floor mats as well. No leaks in sunroof. When I put the car in drive, I can floor it and it will barely move, then gradually go 5-10 mph for a about 10-15 seconds before it takes off. It has no problem going in reverse. It also does this when it rains very hard. As I was driving home yesterday after a hard rain, every time I would stop at a stoplight the engine acted like it was going to turn off, when the light turned green I floored it and barely made the car move. What is causing this problem? I called a service guy at our local Pontiac dealership and he'd never heard of such. Thanks