[Guelo81]

My XC90 randomly started consuming too much fuel. A tank would last over 400 miles and now it barely makes it to 300 miles. When cruising I can see the MPG fluctuate from one moment to another. Like at 55mph it usually does about 26mpg and now it drops to between 16-19 mpg. I had already changed spark plugs, filters, done a few intake and fuel tank cleanings in the last year. Recently I disassembled the whole exhaust system and cleaned all 4 cats and O2 sensors. Exhaust manifold gasket was bad so it was changed and the power is there now. Also, just replaced the PCV valve. I checked the intake and exhaust solenoids and they seemed ok. I removed the fuel rail, cleaned the injectors and put a new fuel pressure sensor since it was not expensive but none of it seems to have helped. I am a bit lost into this whole thing at this point.
Only codes related to that are ECM-P017100 & P017400.(System Too Lean (Bank 1 & Bank 2))
I have used VIDA and D5T5 to run diagnostics but no real answer there.
Any suggestions would be appreciated.