My lo-mile Bird is 28 years old. So are the parts on it. I had a P171 code come up so I started to check vacuum lines, then I checked the PCV valve and found it stuck shut. It wouldn't rattle. For 1.03 I replaced it and what a difference. So I started to replace all the vacuum hoses and found them to be rotten crumbling in my hands. If you have the time its just good preventive maintenance, it can save you big headaches later.