After reading many threads on bad gas mileage, I just ordered a Denso oxygen sensor from Rock Auto for 38 bucks. I'm pretty sure I put a Bosch in mine last time. I'll try to update this thread with my results. I've read some negative post about the Bosch sensor, but no specifics. Can anybody tell me what experience you've had with them?

Hey 97gearhead,

you would probably get better exposure if you posted your own thread.

Right you are! I'll post when I have some results from my new oxygen sensor. Thanks.

I have a Bosch 02 in my 96 installed before joining the BC and I get 31 MPG highway. If it even hickups that bosch is outta there.
I just found with my 90 that the platinum tipped plugs didn't perform as well as a standard Champion copper. I went from RS12'* to RS14'* in heat range and my mileage improved dramatically to close to the EPA numbers. The plugs look chalky white color when removed. I do a lot of around town driving with this car.
Are you running standard Delco'* or platinums?
Also have you run fuel injector cleaner lately and checked if the TPS is set within range.

They're just standard AC Delcos, not platinums.

I've been using FIC for a while (every other oil change) and I fill up at Marathon that use STP additives to keep it clean (if it works or not I doubt it).

I've been discussing this with MyLittleBlackbird, we've (mostly him and Boosty) thinks I might have killed my charcoal canister by overfilling it minimally (multiple times) which can cause bad mpgs. the TPS has been replaced.

Not sure of why you are messing with your canister. If in doubt, get a replacement at the bone yard and see if that solves the MPG problems.
As for the plugs, if your supercharged the NGK TR55'* are performing great.
On my non supercharged SSE the Champion RS14YC6 perform outstandingly with noticeable power increase and MPG.
Both are inexpensive plugs to buy.
The cost of gas @ $3 per gal. is worth your while to bring the MPG'* up.