I have not taken my step 2 yet..taking it monday.. but after reading a variety of different materials, and finishing world random/first time thru with a 70% I'm going to have give in and say that the kaplan book series, yet again, is money. In terms of the info covered and the points emphasized.
I read step up cover to cover, and while great for your IM rotation, this in my opinion is not a good consolidated source of info FA medicine.. is general. It will get you the most common questions.
If you have an area you are particularly weak in, I strongly advise you flip to the kaplan IM book, and just read at the minimum the diagnoses/treatments sections (that's really all you need). Kaplan pedes to me seems to be written fairly high yield as well. Strongly recommend atleast skimming through the important topics in these books.
Edit: Just realized you were talking about IM shelf.
I did well on my IM shelf.. some where around 97/98. I used kaplan IM, cover to cover once, highlighted the important points, and skimmed it again. It pretty much got me everything I needed to know. Then I just did random 44 blocks of IM questions from USMLERx (about 700 before I got bored). The cardio section in kaplan is a bit confusing--I used uptodate...defenitely take advantage of that website for points not elaborated well in your books.