Unknown Wire: 5.0 L 1991 Mustang
 

Hi.
I was doing an injector cleaning and general engine bay clean-up. I found this wire ... I have no idea if it actually belongs to the car or not.
Anyone ever see this wire? It has a heat shield and the wire is red. One end is stamped with m-3-18.

Stumped.

Thanks

Russ
https://cimg5.ibsrv.net/gimg/www.cmo...7c390270dd.jpg

That looks like a vacuum line...look around your throttle body or EGR valve for vacuum fittings with no line on them. If you have a vacuum leak, it may cause the car to idle erratically, and you may hear a hissing noise under the hood with the engine running. If so, that might help you track its location down if you can't find it by looking.