Air suspension keeps going down on one side

Hi welcome main problems are the abs valves causing the 3 dash lights (search 3 amigos online) a really badly sited compressor can cause air suspension models to fail giving the bags a slow leak the V8 is a solid engine but can have radiator expansion tank and cap failures
the other issue is electrics windows and door looms are problematic

dear,,,you need to change air baloon, it might leaking.

Usally there's only one either your going to have to change it again and see how that goes. After u run all the poop gas out. If that don't work u could have damaged a injector ..

We do not have diesel LR option in the USA market so have not info.

Only the rear suspension on the Disco 2 was air. The Disco 3 SE & HSE had air front and back.

possible air leak use soapy water and spay bottle to locate

SPRAY REAR AIR BAGS WITH SOAPY WATER AND LOCK FOR BUBBLES. dOES NEW PUMP KICK ON?

ur cars fuel pump is located inside the fuel tank on the rear cargo

Could well be a fueling issue, best to change the filters and try it again. If it's a TD5, the throttle potentiometer can go faulty and needs checking.
Your suspension issue will probably be a faulty air bag or valve block, and if you don't sort it your compressor will give up also. Check the bags with some soapy liquid and see if there are any bubbles. Typically this comes from the very top. Park on level ground, put the vehicle in extended mode and carefully apply the liquid to see.

listen for air leaking from the bag or the air supply line