My 99 e300Td started missing while on a trip. I am a bit ignorant on diesel trouble shooting so I'll ask you gurus.

Symptoms

Start and runs great when cold. Smooth - no missing.
After warming up will start losing one cylinder. When hot cylinder will runn partialy or not at al. Nost of time runs partialy.
Highway speed is okay with normal power or close to it.
Check engine light came on and is staying on.
130K miles
No leaks, filters always changed.

If I need to do compression check what special tools are needed? I assume I pull the intake manifold.

Please pass you r knowledge along.

I'm suspecting a bad valve seat.