Car maintenance question?

I have a 2004 jeep liberty that will not idle or start on it's own unless I rev the engine for 20 minutes. Pep boys charged me 89 for an engine inspection and I'll be damned if I let them charge me 589 for the full maintenance. They say I need to do a fuel system clean up, like my fuel injectors but I wonder if I can get by with just the fuel injector cleaning fluid. Also they say my idle speed control motor needs to be replaced which I'm sure I can do myself.

Thoughts?