Hi i have a Volvo XC90 3.2L FWD with 122,250 miles on it roughly. I recently replaced the rear cats and muffler, as well as cleaned both upstream cats by soaking them in laundry detergent overnight, and then rinsing very thoroughly. I also replaced all the Gaskets and hardware from the exhaust manifold to the rear muffler clamp, and everything in between. Ive currently put almost 200 miles on since, and for the first 50 miles everything went good after i cleared the cat efficiency codes P0430 & P0420, then the code popped for Bank 1 again. the exhaust seemed to be loud a little again so i retightened all of the manifold bolts, cleared the codes and everything went good for another 50miles until it popped both efficiency codes again. This time i decided to check the 02 sensor live sensor data and noticed that the Bank 1 Sensor 2 was behaving differently from the Bank 2 Sensor 2 via the live voltage graph.(I did make sure the car was at running temp as well) After almost ordering a new sensor, the codes decided to clear themselves with just 15 miles of driving. I assumed this would be the end of it until just almost 50 miles later the efficiency codes both popped again. This time i put all the live graphs for all 4 sensors side by side and here and the readings i got.

Bank 1 Sensor 1(mA)- Lowest reading -0.01(mA) with a high of 0.04(mA) during idle, high of 0.24(mA) at 2,000rpms

Bank 2 Sensor 1(mA)- Lowest reading -0.03(mA) with a high of 0.03(mA) during idle, high of .55(mA) at 2,000rpms

Bank 1 Sensor 2(V)- Lowest reading 0.040(V) with a high of 0.780(V) during idle, dropped to 0(V) at 2,000rpms

Bank 2 Sensor 2(V)- Lowest reading 0.040(V) with a high of 0.835(V) during idle, dropped to 0(V) at 2,000rpms

At this point I'm not sure if the sensors are functioning normally or if the cats are shot, but the upstream sensors seem a little suspicious to me but that's why am asking someone to analyze this data if possible. Another thing to keep in mind is i soaked the sensors is gasoline overnight and then sprayed with crc brake clean then let them dry before installing but during my soak process I did have them submerged entirely to where the top portion where the wire come out was under gas the whole time. Also some things that may be helpful the car does sound like it has a minor whistle which i assume to be a small vacuum leak, The vacuum pump on the car is leaking oil(have a rebuild kit on the way). But the whistle sounds like its coming from the left lower front side of the engine by the oil filter housing, it is one of those plastic ones where u have to replace the filter. so i ordered a new housing for it, with a new o-ring.(i do always torque it to spec also) and some new o-rings for the dipstick as well.