O2 sensor PO135 again?? Help!

   I just bought this 1999 Camry V6 it has 174000 miles. Yea a lot of miles but it was affordable. The check engine light was on so I took it to have the codes read at AZ. It pulled a PO135 O2 sensor bank 1 sensor 1, and a PO446. So I thought do the easy one first, I replaced the O2 sensor, bank 1. Went back to AZ had the codes reset. The light went out, stayed out for one day and came back on. So my thought was time to look at the Evap. system. But to make sure I had the codes read again. Sure enought the PO446 was there but so was the PO135 again. The guy at AZ said to check the plug, I did nice and tight, he also said to check the fuse??? What fuse? Help with this guys. Also any advice on the evap system??? I''m real particular about my cars and like everything right.

PS: Yea I know timmimg belt time again, I have one on order should be here next week. My son a 3yr Nissan mechanic is helping me install this.

P0446: Evaporation Emission Control System Vent Control Malfunction.

The computer has detected condition is one of the below:

No continuity between the vapor pressure sensor and charcoal canister (hose plugged or leaking). 

No continuity between the vapor pressure sensor and gas tank (hose plugged or leaking).

Once the EVAP system has been purged pressure in the canister is equal to the atmospheric pressure (a leak).

Toyota has a TSB on this code to inspect the hoses between and pipes between the EVAP VSV and charcoal canister for leaks.  Replace the vapor pressure VSV and canister.   Suggest starting out by checking the vapor pressure VSV, this is the vacuum valve on the canister.

P0135 is sensor heater or heater circuit malfunction (short or open circuit).  Check the sensor heater and wiring.  The circuit current draw either exceeds 2 amps or is less then 0.2 amps thus setting the code. 

Some owners have had trouble with brands other then Denso and Toyota OEM.

Thanks for the input. After doing some extensive reading on this sight, I realized I have changed the wrong sensor out. I changed the one on the front side of the V6, which is apparently bank 1 sensor 2, I need to change out the back one bank 1 sensor 1. Luckily I kept the one I took out, which is still good, I''ll put it back and put the new sensor I bought in the rear(firewall) location to see if this works.

Yes I changed the back sensor and the PO135 is now gone. I just put the sensor I took out of the front into the back location and this worked. Now I''m working the PO446 evap. code I''ve started with replacing the fuel cap, if this does not work the VSV will be next.