What is the code that their scanner is showing?(this will get better help from gear heads) I would guess it says something to the effect of "lean bank 1". when the scan tool pointed at the bank one sensor that meant that sensor saw a problem or possibly was the problem. If you changed the sensor dont go buy another one until you rule out the following.
1. fuel pressure (you might not have enough and your really running lean)
2. vacuum leaks (will also cause a lean situation)
3.clean battery terminals (this can and has caused the same problem for members here)
As stated above people here don't like Bosch sensors because they fail early, a simple scan tool can tell if the sensor is bad by the rate the voltage toggles. I wouldn't replace it until you know it'* bad.
Gutted air box, K&N drop in, MAF screen put back in , NGK tr-55 @ .55, 180* drilled t-stat, INTENSE 3.4mps, Aeroforce, High-flow cat, and one BIG F-ing smile.