the check engine light was on 3 months ago, but the shop cleaned the oxygen sensors. so now, they are off.

Still, if they did clean the MAF sensor - that is a little unusual, as most shops would rather replace it than try and clean it. With the mileage you have on the car - I highly doubt it would be an O2 sensor problem, unless it was a faulty part from the beginning or something damaged it recently.

Did the shop happen to write down the exact CEL code that was present at the time - should be on the work order sheet somewhere? This would greatly narrow down the field of possible causes.

As it stands - I would check the normal maintenance items (filters, obviously loose hoses, bad connections, loose wires, etc.) and then look into two key systems - fuel and ignition. Make sure that the car is getting enough fuel when you accelerate (can be done by t-ing off the fuel inlet line with a SST) and that the injectors are in good, working shape. You can try using a fuel injector cleaner - good ones are made by Red Line, Chevron w/Techron, Lucas, etc. and see if that has any affect. Could also try running one step higher octane to see if the engine responds any differently. Fuel filter in inside the fuel pump assembly - but usually lasts a good, long time - if they find a fuel supply issue, then I'd look into them testing the fuel pressure regulator, fuel pump, filter, pickup, and all hard lines. Ignition - make sure that you are getting a good spark in each coil pack - harder to check because of their design, but still doable. Pull the plugs and "read" them - see how the deposits nad coloration varys from plug to plug (should not be much difference). If there is a significant difference - that could mean a problem from the clyinder(s) that the plug(s) came from.

From there - work outward and look at the other systems - exhaust, induction, EVAP/emissions, electricals and sensors. You could some simple cleaning of some parts - to see if that improves anything. A poster sniffer - has a recent topic that included some very good DIY links as well as some before/after pics:

https://www.corolland.com/forums/index.php?showtopic=20061#

If that doesn't do the trick - then I'd go after the most common component that can create a significant drop in fuel economy and power - the O2 sensor (most of the time, it is the upstream one - or the one closest to the engine). If not - then you are looking at the other end of the spectrum - as these symptoms can also come from a faulty VVT-i system (just do a search here on the forums). Not a inexpensive project - happens farily rarely, but can happen. As mentioned before - a specific code can help narrow the field - otherwise, it would be just like throwing darts at the wall. Good Luck.

You'll probably be charged a diagnostic fee - probably on the order of $80-$90 to start. Just tell the service writer what your car is doing right now (ie. your topic that you posted here) and they will suggest different courses of action. If possible - talk with the technician that worked on your vehicle - as they may have some useful information that useful later (a technician cannot write all the little details on the work order - as most are normal wear and tear items, but can be useful later if the diagnosis drags on).

Most shops that perform the diagnostic takes a general overview of the issues at hand - a good shop should note anything unusual first before suggesting part --- is bad. Almost all will scan the onboard computer for stored trouble codes, as cars from 1996+ are OBD-II compliant and information logged there is extremely useful for a successful diagnosis.

For this type of job - I would take it to a Toyota dealership or reputable foreign car independant garage. As they have the experience and knowledge to quickly eliminate non-issues and get to a possible cause to your problems. Good Luck.