As a new owner of a Disco I and I can't leave well enough alone, I have changed all fluids in the Discovery and gone to synthetics throughout. And even a complete power bleed on the brakes. Went to a friends BMW shop and used his transmission power flush on the transmission. Now I know where my starting point will be on the fluids.

Today I installed a K&N cool air induction tho help the engine breath.
The 4.0 engine is a lost spark engine and the plugs and wire have to be in tip top condition, or a bad plug or wire will take out a coil$$$$$$. So off to my son-and -Laws dads shop, they race NASCAR ARCA and build their own engines. He buys 8mm strain ignition kits in bulk. So we made a set for the discovery. I used his OBII dino to check the peramiters and to adjust the CO. and no Cats.

The truck came alive .