Sluggish and bad gas mileage 95 V8

Suddenly my mileage has really dropped, and my 95 GC limited seems a bit sluggish. Not running rough, just seems like I'm going uphill.

I did the most obvious, changed the air filter. Am about to do plugs, cap and rotor (man the cap and rotor are a pain being back there...)
Anything else I should look at?

O2 sensor

Wouldn't an O2 sensor throw a code?

catalytic converter could be clogged

Well the exhaust sounds the same as always, and the cat isn't very old...

I pulled a spark plug tonight, looks pretty good.

Is there an easy way to test for a clogged, or partially clogged cat?

cut it off :)

I did mine . it works