Sorry,been busy - P0130 means slow response,upstream sensor,bank A.So you have not caused this by removing the cats,if you have immediate access to a code reader I suggest you swop the upstream sensors from side to side - you should get code P0150,(sl res ba B) this will prove that the sensor is ageing and incapable of responding quickly enough.
If it stays with P0130 then you need to check if the sensor is being heated properly,earthed properly etc.You can compare readings from bank B to decide which is correct.Your sensors are Titania ones which will give a constant 5v output from the black sensor wire if they are not heated enough to make them switch.They are also the opposite output to Zirconia ones in as much as they read lean at 5v and rich at 0v.(Zirconia - 0v,lean - 0.8v rich)
Have a play around with it let me know what you find,sounds to me like a simple bad connection or a sluggish sensor,I dont think its too serious.Good luck.
P.S. I'm away now till Monday,catch you when I return.