View attachment 66235That looks like a massive vacuum leak, right there, plus that's the PCV system, that puts a light vacuum on the crankcase. That TEE is the one with the restrictor in, that can get clogged too. It's plastic, so be gentle! With the engine idling, if you cover the end of that metal pipe, the engine speed shoudl reduce dramatically. That thinner black hose should be on that metal pipe.
Air should be whistling in there! I'd be VERY surprised if that wasn't you idle issues (mostly!).
And you need a fan shroud.
I have that same radiator. Without the shroud, the fan circulates more air than it pulls through the radiator, the temp creeps up to 100C and the electric fans kick to to cool it down.
With the shroud on and a functioning Viscous fan, my temp sits between about 87 to 92C at idle and cools quickly as the engine speed increases. I'd get one for sure.
There is a little blue fitting on the firewall behing your throttle. Does that connect to the rocker cover, and the airbox? There is a hose that should, similar diameter to that.
The air filter would normally bu much further back - the MAF wiring just about touched the washer fluid bottle! If it's backfired that much (on LPG I assume, igniting in the intake!) the MAF might not be too happy either. In Aussie, just about all EFI Discos would have that that housing, or the round cylindrical one made of metal. Any plastic one should work, thought yours must have a "custom" mount under it, or extra mounting holes etc.