'80 240D: Are injectors bad?

The car has 130,000 miles. It feels like the engine has a bad miss when accelerating and an occasional miss when cruising. It starts up fine when cold but is hard to start when warmed up. It idles decent when warm and it doesn't smoke when accelerating. I've replaced the fuel filter and adjusted the valves with no real improvement. Should I start by removing the injectors? Can they be taken apart and cleaned or should I just replace them? What about testing them first? How much should a shop charge for testing?