I've got an 03 CTS with 37k miles. Beginning at approximately 3k miles I started getting a check engine message indication after running the car through the automatic carwash or during a heavy rainstorm. The car would then shake, idle rough and is robbed of power. Re-starting the car sometimes cures the problem until the next wash/rain. Three dealerships have tried repairing the problem. They all claim the problem lies with the coils. They have replaced all coils several times and "sealed" them as well. This works for a while, but the original problem always returns.

The original factory warranty expires at 40k miles and although the issue is well do***ented I don't want to have to go down that road. I really enjoy the car otherwise and don't want to have to get rid of it, but I'm getting a bit concerned.

Has anyone out there experienced a similar problem?

Any information would be appreciated.