some advice needed....

hello all, this is my first post here. I just picked up a 73 450sl from a relative. The car has been sitting a few years and I have a feeling im going to be doing some work to it as it has pretty low miles. I would like to start with a good repair manual being I can work on cars.... also the last time I was in this car it had some sort of idle problem, in park it goes from 1000 to 2000 rpm like it has a big cam. Thanks for any replies...Dave.