2006 3.5L po172 code
 

cleaned MAF sensor, Checked and cleaned out fuel canister up next to filler cap.added fuel cleaner and 93 octane. Cannot find how to check the o2 sensor. still getting same error code. is there another fuel canister the might need cleaning/replacing? Any suggestions?

Several different problems can trigger that code. Faulty wiring, a dirty MAF sensor, leaky fuel or vacuum lines, dirty fuel injectors, fuel pressure, etc. With so many possibilities I would take the vehicle to a dealership or shop and have them do some real time testing and check history so they can narrow down the possibilities. Otherwise you could be chasing your tail forever trying to figure it out...and spending money needlessly.

thanks mike.That is what am facing. Going to clean MAF sensor with sensor cleaner. Was told that injector cleaner doesn't work for this. When they say the fuel canister could be saturated are they talking about the one behind the gas filler door? Or is there another one? The o2 sensor connector is mounted up on the back of the block and that is hard to get too. Checked for vacuum leaks but found nothing.