My 99 Disco 1 starts up perfect and smooth every morning. Runs great. And if it has sat for 2 hours or more it starts up perfect and runs great.

However, if it's been less than a few hours and the engine is still warm, it starts really rough or doesn't start at all. And if it starts rough, it never smooths out.

What's up?

 

And it's pulling run rich and miss codes.

 

Cold engine needs more fuel. Purposely runs rich. Which is why it's fine when cold. You need to find out why it's always running rich. What maintenance have you done? What codes are you getting?
Start w basics first. Vacuum leaks O2 sensors ect. Then work your way to more complicated problems.

 

Check coolant temp sensor, intake air temp sensor. Do you have a real time scanner like ultra gauge ?