I have a 2006 DTS that we bought at an estate sale with 12000 miles on it in 01.16. It now has 26000 miles on it. It sat garaged for 5 years after the first and only owner, 90 yrs old, got sick and finally dies. Pristine shape, new battery, oil change, ran great. In Jan of this year, got stuck in a torrential down pour and water came up to the bottom of the doors while we tried to drive out of a street that was flooding. I punched it because I didn't want water backing up into the mufflers, so off we went and we kind of looked like a uboat cutting a wake for a couple blocks. The next day, while idling in a parking lot, the engine rand rough, then fixed itself. Since then, the engine has done some funny things. Several times it has completely died and threw a P2431 code, (back in April I replaced the air injection system pump even though it appears to be working fine) The engine since then has thrown only one more code which had something to do with the 'traction control system'. The car stuttered, then the code came on and but the engine didn't die. It shifted hard was we drove it home, after turning it off, at home, and back on again, NO code, no shifting problems then or ever since. Now, the car dies about once or twice a week. Just dies. NO codes on the dash. IF you are at speed, the engine restarts apparently because the tranny keeps it turning over and it restarts. If you are stop and go, parking lot speed, it just dies, but Restarts immediately. The wife was driving it down a steep hill with tight turns when it last happened, at night. NO eng, NO lights, practically NO brakes and NO power steering. By herself, scared the ****e out of her and now she wants me to take it out and shoot it. Anyway, any ideas? I have heard GM products have always had issues with rust at ground connections, I am betting the rain had something to do with it.