Chrysler Repair: 99 T&C hesitating on acceleration, chrysler town and country, o2 sensor

Question
I have a '99 Chrysler Town and Country, 3.8L. Everytime the vehicle is started it idles rough for a short time then will rev and run normally. If the vehicle is driven before it revs and runs normally it will hesitate with acceleration and then suddenly surge, but this hesitation and surging will only occur for a short time after the vehicle is started, otherwise it runs normally. I can also hear a loud noise coming from the resonator during this initial period (I think it is refered to as blowback into the crankcase). There is also the code P0138 coming up on the scanner. Any help with this problem will be greatly appreciated, thanks.

Answer
Symptom:
P-0138 1/2 O2 SENSOR SHORTED TO VOLTAGE
When Monitored and Set Condition:
P-0138 1/2 O2 SENSOR SHORTED TO VOLTAGE
When Monitored: With the engine running for more than 2 minutes and coolant
temperature above 76 degrees C (170 degrees F).
Set Condition: The Downstream Oxygen Sensor Signal voltage is above 1.2 volts.
POSSIBLE CAUSES
1/2 O2 SENSOR SIGNAL CIRCUIT SHORT TO VOLTAGE
1/2 O2 SEN HARNESS INTERMITTENT SHORT TO VOLTAGE
1/2 O2 SENSOR CONNECTOR OBSERVABLE DEFECT (A)
1/2 O2 SENSOR CONNECTOR OBSERVABLE DEFECT (B)
1/2 O2 SENSOR HARNESS OBSERVABLE DEFECT
1/2 O2 SENSOR DEFECTIVE