If you haven't changed your plugs and plug wires in the entire 130K miles, then I would say that is a good place to start.
When I put a Code reader on my car I got 6 codes,
1. Said O2 sensor had "slow response"
2. Catalyst efficiency below specification
3. O2 sensor inicates lean
4. Random/Multiple misfires
5. Fuel trim system lean bank 1
6. Fuel trim system lean bank 2
I am going to try the following in the following order:
1. Injector cleaner for the next few tanks
and
2. 2 new O2 sensors
then
3. New catalytic (but ths is like $300 for a stainless one from
www.batinc.net).