O2 Sensors and Misfire Detected

[geoech1]

I have hestitation at idle around 500 rpms. Here's what my Scan tool says. I understand which sensors are which, but can't tell which one. :-s Could someone try to help me. Thank you.

 

General Information

 

VIN: 2GTEK19Z......... Report#: 101 Vehicle 2007 GMC Sierra Date of Report:

07/05/2012 1:36:03 AM (EST) Engine: V8, 5.3L; FFV Mileage Reported: 88000 Trim Level: SL; SLE; SLT; Work Truck Transmission Reported: Automatic Powertrain Diagnostic Trouble Code Information MIL DTC P0174 System Too Lean (Bank 2) Stored Codes P0151 O2 Circuit Low Voltage (Bank 2, Sensor 1) P0174 System Too Lean (Bank 2) P0300 Random Misfire Detected P2A04 O2 Sensor Circuit Range/Performance Bank 2 Sensor 2 Freeze Frame Infomation Parameter Description Results DTC for which Freeze Frame was Stored P0174 Fuel System 1 Status Closed Loop Fuel System 2 Status Closed Loop Calculated LOAD Value 25.49 % Engine Coolant Temp 195.80 °F Short Term Fuel Trim - Bank 1 0.00 % Long Term Fuel Trim - Bank 1 0.00 % Short Term Fuel Trim - Bank 2 26.56 % Long Term Fuel Trim - Bank 2 25.00 % Intake Manifold Absolute Pressure 13.32 inHg Engine RPM 513.00 rpm Vehicle Speed Sensor 0.00 mph Ignition Timing Advance #1 Cylinder 23.50 ° Intake Air Temperature 98.60 °F Air Flow Rate Mass Air Flow Sensor 0.96 lb/min Absolute Throttle Position 18.43 %