OK today hooked up the Rover to a scanner and the results are as follows,
P0308 #8 cylinder misfire, and P1187 O2 sensor. i have not replaced the plugs or wires yet. Like i said the truck runs normal despite it running rich. so does anyone have any ideas?

 

Bad plug / wire ,, bad 02 sensor.
Classic Disco's need the 02's changed at 82,000 miles has that been done?
Even if the 02's have been changed you can have a bad one or mess it up on install.

If you keep running rich get ready to replace your cat's.

 

Replace your plugs and wires first. A lot of O2 codes are caused by bad plugs and wires. How many miles on your truck? Regardless I am thinking that your O2 sensors are near dead since the truck is a 98. Running rich will destroy your cats like landzu said.