I have a 2002 montero sport that ive owned for a while now, unfortunetly I need to pass emissions now lol. the current issue is the check engine light with egr valve codes.
P0403, P0401
note I have replaced: egr valve, solenoid EGR (I think P0403 went away after I replaced the solenoid), cleaned out the EGR passage (took off the intake and pipe) and the Manifold differential pressure sensor.

what else can I try? maybe cleaning all the conecitions?

 

should i make a Youtube vid? the EGR valve appears to be working now it opens and then closes slightly when you rev the engine