Volvo: volvo s80 1999 runs bad at running temp, mass air flow sensor, mass air flow

Question
I just purshaced a 1999 volvo non turbo s 80 . Had it checked at the dealership,they said it needed a mass air flow sensor and the rear o 2 sensors. The fronts have already been replaced. When the car is cold it runs fine but when it heats up its like its only running on 3 cyls. I replaced mass air flow but still does same. Will the rear 0 2 sensors cause this problem?

Answer
Dusty,
O2 sensors will sometime affect the way the car runs, but not to the extent of causing the car to feel as if it running on three cylinders. Is the check engine light on, or is there a vacuum leak, a fouled out plug? Those are the more likely things that cause a rough running vehicle.