Every time I start my dryer it squeals for about 3-5 minutes, yet runs normal. It is a very high pitched earpiercing squeal, so loud you can't stand to be in the room with it. I think it's the idler pulley but don't want to order parts until I'm sure. Anybody have any experience with this problem?

What brand and how old is the unit? Open back of unit up and start unit. You may be able to see where noise is. You are correct, don't buy parts until you know what to get.

I have a Maytag Atlantis model MDE7657AYW purchased new in 2002

My very old dryer did the same thing. It has gotten to the point that the inside would not spin but it still gets hot. I figured it was the belt, I could smell burning rubber. :(

It very well could be the idler pully but I would open unit up and watch it on start up. These units have had a problem with sticking idlers. They just seem to bind up. A couple times I've seen belt slipping and can spray with belt dressing to cure problem. I would look and listen and it should become clear. Good Luck and post back with results