I'd start with the easy stuff first & work my way to the more complicated.

1. Dump some injector cleaner into the tank at your next few fuel stops.

2. Remove spark plugs, Clean them (or replace), Gap to .032. Mebbe crank the engine a little with all the plugs out before re-installing plugs.

3. Clean MAF, TPS, FPR, & EGR

4. Have a muffler shop check your exhaust system for any clogs/leaks (your cat may be on it's 9th life).