To me it looks aftermarket, you could try check the ground and the brown wire looks pretty dodgy so you could try to resolder that if the connection is bad. Having the diesel the only sensor I have around the airbox is the air sensor which just tells you if there's a restriction eg clogged air...
I've had that happen, usually it's just gear wind up and driving straight in reverse, forward, reverse usually pops it out for me but seeing you've tried that, pull a drive shaft to relieve the tention? I'm not sure.
I'd be checking the glow plug relay, connections and earths associated before going out and buying an alternator, does your voltage gauge go down or is level while driving?
Replaced the front door hinges. Now closes much better and lines up with the rear door again!
I did the job myself sitting on my side step and supporting the door with my knees while removing and installing it. Fairly straightforward and satisfying job
Fitted the custom Loncky leather steering wheel cover to the factory rubber one. No sewing experience prior if you're interested in these all you need to know is how to tie a knot and thread shoelaces lol.. Comes with enough string to do 5 wheels, it was a little tight in some places so in a few...
It would be interesting to see how they came up with dropping the front diff on a 105 series lol
The main thing to worry about on those are the caster correction bushes are installed in the correct orientation as they're eccentric. These allow the diff to maintain proper shaft angles in...
You could check the EGR or intake isn't gummed up, Injector clean and compression test but if the engine isn't smoking or has excessive blowby probably won't be the case and those engines are built like a tank too. I'd be more inclined to get the trans looked at due to what you're describing