my car has 190,000k and when its in park it shakes and you can watch the rpm's flutter up and down 100-200rpm, if i pop the hood the engine is shaking like crazy

and is ticking.
Also once in a while i will be driving along and when i stop i can hear a constant rattling sound (like a chain dragged over a glass bottle. quite loud
i get regular oil changes, but i was told you dont need to service the tranny... bought the car at 120,000k should i be doing something with the tranny or is it to late to start???
PLEASE HELP!