Toyota Repair: 2000 Solara Check Engine Light, toyota solara sle, air fuel ratio

Question
I have 2000 Toyota Solara SLE V6 Coupe. 57:3 OL 2995CC V6 FI VIN: 1MZFE. The vehicle has 190,000 miles on it.  I bought it used with 109K. I had been averaging 25 MPG with mostly highway driving.  The My check engine light came on and I noticed the car running a little rough.  My MPG went down to about 22.5.  If I shut the car off and run into a store for 2 minutes and start it again, it immediately stalls.  Sometimes it takes 3 or 4 tries to keep it running and I have to press the accelerator to give it gas so that it won't stall.  Then it's okay. I had the codes pulled and this is what I get:

P1150 - Air/Fuel sensor circuit range/performance. (bank 1 sensor 2)
1. Open or short circuit condition
2. Poor electrical connection

P1155 - Air/Fuel sensor circuit range/performance. (bank 1 sensor 2)
1. Open or short circuit condition
2. Poor electrical connection

In doing some research, I found a Toyota Service Bulletin that showed diagrams of the various air/fuel and oxygen sensors on my engine. According the diagram, my vehicle has 2 air/fuel sensors AND 2 oxygen sensors. And if the information is correct, Bank 1 Sensor 2 is an OXYGEN Sensor. I have been told that it is downstream so that would be after the catalytic converter?  My questions are, is this likely the only problem?  Should I change more than one sensor?  If so, which one or ones?  Also, is this something I could do myself with the car up on ramps?  If not, I'm afraid that my Toyota dealer will charge me $1,000 or more to fix this.  Any help will be appreciated.

Answer
Hello, both of those codes indicate a malfunction of the air/fuel ratio sensor bank 2 sensor 1, AFR sensors are always in front of the catalityc converter, in this case the sensor that should be replaced is in the exhaust manifold near the radiator and is visible under the hood, i'ts not hard to replace but you may have to by a special O2 sensor socket from the autoparts store where you buy the sensor, try to stay with the OEM brand sensor which is made by Denso. At this time I would only replace the bank 2 a/f sensor and clear the code by dizonneting the battery for about a minute.