2004 crv ex japan made acceleration issue.at my wits end
 

hello all
my wife has a 2004 cr v ex.it is the japan made one.it is losing power,losing acceleration and bucking after warm up.it is worst on hills.i have replaced,the iac valve,both cam sensors,fuel pump and pressure regulator.the only codes i am getting are for the vtec oil pressure switch,and the upstream (front) o2 sensor.does anyone have any suggestions about which,if either,of these components could be causing this problem?i replaced the o2 sensors a few months ago,but with parts from advance auto parts,not the honda dealer.if anyone can offer any suggestions,it would be appreciated.thanks

Does it feel like the the engine has no power, or like the engine is running faster, but not getting power to the wheels.

You said it was bucking, so I'm thinking of a transmission issue, maybe.