1999 Mazda Millenia Check Engine light flashing

Engine Mechanical problem
1999 Mazda Millenia 6 cyl Automatic 20,000 miles

We had extremely heavy rains causing high water, I drove through slowly. My check engine had been on steadily, but after going through the water the light is now flashing, and the car seems to be idling rough and I have noticed a change in power and fuel economy since this occured 2 days ago. I thought it possibly needed to dry out, but it is still occuring and I also now hear a noise from the engine, almost like a whine from a power steering belt, but not that loud and it is constant