Bank 1 is just the designation for the front Oxygen Sensor, the one before the catalytic converter. What the code indicants is that it has seen a prolonged lean burn condition or has seen a lean condition more than a few times.
You may be on the right track by checking for vacuum leaks, the PCV elbow is prone to deteriorating and the whole intake tract is prone to oil mist than may or may not be an issue (gummed up valves, gummed up Idle Air Control Motor).
You may want to try sucking some sea foam through a small vacuum line into the running engine. Some have had luck doing this, I personally have not (but I have bad luck the way it is).
It may have just been a fluke and a result of a bad tank of fuel. It does happen.
Or it could be a failing Oxygen Sensor. I believe most good shops are able to test the O2's response time and see if it's life is nearing the end. Generally when they fail the response time goes way up, or is just nonexistent.
There is also the known Fuel Pump Module problem. But fuel starvation around corners and under heavy load are generally associated with that problem.
The simple things you can do are check for vacuum leaks, which you did and are doing. Replace the fuel filter, lets say if it has not been done within the last 20,000 miles. Check the spark plugs and wires, misfires or poor combustion could be to blame.
Other than that I would say to get it checked out so you're not throwing money at it and wasting money by fixing good parts.
