If it has never been done before, it might be worthwhile to do the fuel system clean out. This is a dealer favorite way to get a quick hundred bucks. But in 100K miles it may be worth it. All they do is hook up a machine that pumps intake and injector cleaner into the fuel rails. Very simple very cheap for them to do. You could use an aftermarket additive for a few tank fulls. Or I think there are some do it yourself kits available.
Fuel filters need to be changed probably at least every 50K.
One other thing that would be worth doing at this many miles is to clean your throttle body. This usually requires removal and cleaning with brushes and solvents.
If your tranny has never had the fluid changed or it has been 50K miles or so, I would have the fluid changed. Not sure if I like flushing but then the LS appears to be a PITA to do a normal change. Be sure if they do this they use the right spec fluid. The trannies in our cars are a bit finicky and I believe the fluid is semi or full synthetic.
You can also expect the O2 sensors to be getting flakey. To be cheap I think only the first set need changing. These are the ones nearest the engine and they get more of a workout than those downstream from the cats. This is a routine maintenance issue, like spark plugs.
Good Luck,
Jim Henderson
