Gents,
I have a 2004 Discovery II and have benefitted a lot from the help on LandRoverForums before. I got a divorce and needed 7 seats for my kids so my friend sold me his dad's 2005 LR3.
I had to replace the rear end but everything else has been great.
I have reently been experiencing engine stall at low speeds, "reduced engine performance" warnings, and even intermittent yellow check engine lights. Some people have talked about replacing the diode, but the majority of what I have read talks about the throttle body needing to be cleaned from all of the black oily gunk.
I went to undertake that job and decided to inspect for any troubles with hoses and found this.

Whatever that hose is, it seems to be leaking on the underside and it has led to a pool of orange fluid (I think coolant, but not sure) where the arrow is pointing.
Does anyone know the name of this hose? I just want to replace it when I clean the throttle body to make sure I am covering both bases. If the throttle body cleaning doesn't fix things, I will buy the coil diode and see if that works too.

 

Take off the intake hose from air box to throttle body.

chances are your plastic thermostat housing is leaking.

 

Agreed, the coolant crossover is probably leaking coolant. You have to remove the throttle to replace the crossover, it would be a good time to clean it.

However, the throttle could be causing the stalling, but usually won't cause a "restricted performance" or "check engine" light. So you should have the engine system scanned for fault codes to see why that light is coming on.

Speaking of coolant, regardless if it is leaking or not, replace the coolant bleeder. Its a plastic "T" with the cap on the middle port, just over and to the right of the throttle. They are thin plastic to start with and get brittle with age. We see lots of these overheat because the bleeder splits and spews all the coolant out.

 

I've had the stalling/REP/CEL symptoms due to a fouled up MAF, too.