Hello. My power steering is stiff. sometimes its not i dont knw why . My tires are brand new 225/40/18 set the tire psi to 38 still stiff. Set it to 36 still thesame thing. My fluid is not low but mazda recommended to.do a steering flush but they said its still too early for it somehow i need to get it done. Any thoughts about it ? Does it have to do with the steering flush? Let me knw thanks..