So tonight I start my car up and it starts to shake very hard while in park/idling. I drive it and while driving I hear a metallic clang during shifting (700R4 auto trans) and I hear this under/around the pedals. Also (this has gone on for awhile just thought I'd throw it in there lol) when I'm at a stop sign/light sometimes my rpm's will drop considerably to around 500 or so and it acts like it wants to stall (I've seen this alot and read various solutions, idk where to start).

So yea....any help would be appreciated! I don't know much about cars...but it'd be nice to kind of get some kind of idea of what's going on before I have to take it to a mechanic or something.