2000 5.3L 100k maintenance

Ok, my wife's truck is getting up pretty close to the big 100. For a few months now it's been a little hard-starting and the mileage has been a little off (12-16 compared to 15-22 when we first bought it.) I'm just wondering what should be done around now..

The big item would be a throttle-body cleaning, but that was done when we first bought the truck about a 18 months and 12,000 miles ago.

i'm thinking plugs, wires, air filter, fuel filter, injector cleaning... what else is there?