Engine or Transmission

I recently started having this problem. My 1997 Dodge Ram 1500 4X2 experienced a dramatic loss in power, with a weird whirring sound from under the hood, about 25 minutes later my check engine light came on. The following day I took it and got the error codes read, I had 3 Cylinders misfiring, numbers 3,7, and 4. Truck was good for a day, and this morning same thing Whirring sound, lack of horsepower. I have asked around and a lot of people say it's a engine problem, some a Transmission problem.. HELP!!!