Bank 1 and Bank 2 too lean?

I have a 2004 ford taurus. About a month ago the CEL came on, ran to advanced auto to get a code and they said my bank 2 was too lean. Yesterday, got a code run again and they said bank 1 and 2 too lean. They said it was probably my oxygen sensors. The car has developed a rough idle when first starting up and has lost some power and acceleration. I plan to take it to a mechanic soon, but until then i'm trying to find out what the problem is. Any suggestions?

Maybe the plastic intake manifold is cracked the way they do on Fords.

Lean both banks, Not enough fuel, too much air. Clean the Mass Air Flow sensor ( Very common on fords), check fuel pressure ( restricted fuel filter), leak in the intake gasket. There's more that it could be. The first thing I would check is for a dirty MAF sensor and you can clean it with brake cleaner or you could buy the special cleaner that they make for it. Just be careful when cleaning it

First your Sensors are fine they detected a lean mixture! You have p0171 and p0174 with drivablity issues… It's usually the rubber hose to or elbow for the pcv valve… It may be one of a number of vacuum leaks. I'd take it to the Ford dealer, some Taurus had a revised hose kit that rerouted the Hoses for the pcv/ccv. Often you'll wait less then half hour. We had a few hundred of these with the Vulcan 3.0…