Definitely pull the plugs and look at them. As stated above, mark the COPs with a sharpie and move them.

Sitting in the car looking forward:
Bank1 = right side
Bank2 = left side

Front
--------------------
Left . . .Right
2 . . . . . 1 - plug (COP) positions
4 . . . . . 3
6 . . . . . 5
----------------
B2S1 . . B1S1- o2 sensors
.
B2S2 . . B1S2 - rear o2 sensors

I'd move 1 to 5 and 6 to 2. Replace the plugs while there and be sure to check the gap.

 

As mentioned by some, try cleaning the MAF sensor. Worked on my 06 IS350 @ 172k miles.

What I did: Cleaned MAF sensor best I could(more than half the can). Disconnected battery, reset ECU. CEL turned off but came back on 30 miles later. Gave it a few days and CEL turned off and stayed off 300 miles later.

For those that have this similar issue, definitely try this cheaper route first, next to replacing your gas cap with a new one.

 

so how does one clean the MAF sensor?

 

CRC MAF Cleaner. Take out Maf and spray. Let it completely dry.