I have a 03 mustang gt. I have a new pcv valve, hose, and egr valve but the pcv valve hose is still collapsing when the car is on. Any answers would help me out alot. I tried everything and so far nothing.
Pull the hose out of the driver side valve cover. If the passenger side hose still collapses then you have a problem inside the engine probably sludge and will need an engine flush. If it doesn't collapse then you know it has to do with that hose.
Rickyll7's probably right: Get an OE hose or one specifically made for PCV applications. Such hoses typically have thick walls to resist collapse and high resistance to hot oil and vapor.