The air injector line from the manifold back into the engine has lost a fitting. It looks like it was a rubber connector about 2 inches (5cm) long and it melted off. The national shops say they cannot get just that line but an entire kit for a couple of hundred bucks. Does anyone know if a junkyard hose (same hose from a wreck) can be installed by a semi-skilled DIY like me.

Secondly, what would cause the fitting/hose to melt?

BTW, this is a 4.3L V6 fuel-injected engine with 175,000+ miles.