Dude: Don't pay them to do a tune up. Do it yourself. Even if you have to tow it home, they are going to charge you hundreds of dollars for $30 worth of plugs and wires. As far as cleaning the throttle body, make sure they are actually going to remove it and clean it. They are probably just going to run a bottle of gumout through it, which you could do at home for $2 or so.
As far the other engine work goes, let them do it... They have the tools and know how to put everything back together right.