My 2003 Land Rover Discovery 2 started misfiring at idle with a P301 code. I ordered new plugs and wires from the states (I live in Costa Rica) and while waiting for them I gave it the Seafoam treatment. Lo and behold that cured the problem - smooth idle and no more codes. But here is my question - while troubleshooting the issue I traced all the vacuum lines looking for broken or disconnected lines that might cause a vacuum leak. I came across a hard plastic line in the loom behind the brake booster that is unconnected and open on the end. I can't find anything it might be connected to, and I couldn't find it in the Rave manual. It might be a vent line for the transmission or something but it's very muddy now and I don't want to lay under it tracing the line unless I have to. Does anyone know what the line next to the arrow in the attached photo is?

Thanks in advance!

Unattached plastic line

 

Front Diff Vent