Hey Jason, It's me again buddy. so on your shower drain odors. Is it only coming from the shower?
i had the same problem with my 95. I thought it was the shower but it was the toilet. The seal on the ball that opens was bad and the water in the bowl would run out and the odor would come past the seal, especially when the bathroom fan was on. So make sure your bowl holds water. If you're sure its coming from the shower drain, plug the drain, let a few gallons of water build up, pull the plug and plunge it with a toilet plunger. Used to have to do that in a mobile home we owned.
Good luck,,,, Lloyd