I've got the same problem with a 94 c220. The MB dealer has replaced the fuel filter, fuel pump, injectors, mass airflow sensor, coolant temp sensor, air filter, spark plugs, vac lines, gas cap, and who knows what else. All that's left is the intake air temp sensor, the engine control unit, and the entire wiring harness. They have had two or three different mechanics working on it, but the problem persists and if anything it is worse. If you have a good independent repair shop close that has all the latest in electronic engine analyizers it might pay to have them check it out. If you find your problem before I find mine let me know what the problem was. The entire ECU system is so complex you can what-if yourself into bankrupcy. I posted a cry for help on this forum, but so far I've only had a couple of replies. Good luck and have a merry holiday season. I've got my Christmas presents sitting in the driveway, even if it is hard to start above 40 degrees.