hadn't thought about a temp sensor - thermostat has been replaced
tried checking for vacuum leaks "before" but who's know may have missed something
working on the O2 part now - it's only drivern 3,000 miles a year so may take a little while to figure it out

Gas price is just getting to the point I ...

I forgot that I did also replace the EGR years ago - probably 5-6 yrs

I'll try and O2 and see what happens

THX

have not replaced the O2 sensor
for the most part in my area I use Speedway gas
any recommendation on a particular brand of O2 sensor?
As far as maint more or less just the routine maint other than changing the plenum recently but the mileage issue was present long before that issue
guessing the O2 ...

Can anyone shed some light on a sudden drop in gas mileage.
Car runs great, no diagnostic codes.
Everything is stock
Replaced fuel filter, wires, plugs....
Cleaned the MAF & IAC
Just over 100k miles
Literally overnight it dropped from a consistent 20mpg (mostly in town driving) to 14 mpg.
Baffled as ...