I had similar issues with my '89 300CE. The car only had about 60k miles as well when I had all the injectors, fuel accumulator and pressure regulator replaced. With age the injectors often leak down internally as others have said. The car could also be starved for fuel, in my case it was running too lean due to the faulty fuel pressure regulator. Additionally, it was not holding sufficient pressure after shutdown due to the defective fuel accumulator. It would often be hard to start when hot ie. long period of cranking and then stalling. After I had all these components replaced the car now runs very well and starts without a hiccup.