you have an O2 issue. Replace them both or buy one new one and put it on one side, if the problem continues move it to the other, if it continues replace both. Two minutes is time for it to warm up and enter closed loop mode and get feedback from the 02s to correct the fuel ratio and they're getting bad readings.

If you have a scanner that will show you the readings and you understand the voltage feedback readings you can quickly figure out which sensor is bad.