Hi "Mercedes Kin!"
I need help which an experienced Mercedes shop owner can't solve. My 94 E420 has 183,000 miles (I bought it new originally). The vehicle was missing badly at all RPMs, both cold and hot. The mechanic replaced the notorious, degraded engine harness. However, after the car sat idle for a day, it ran rough again until traveling approximately 10-12 miles. Then it ran okay except for occasional skipping at idle. The mechanic then changed the mass meter(mass sensor). That was over $500 wasted (no improvement whatsoever). Now he suggests changing the ASR harness ($1000). However, neither the "check engine" light, nor the ASR light presently go on, and REPEATEDLY, the car demonstrates the same pattern for 4 weeks now: Rough running and stumbling the next day until it covers 10-12 miles. Then runs okay (even after shutdown for several hours), except for an occasional skip while idling. The more days it sits idle without running, the worse it runs until 10-12 milles are covered again. Any thoughts? The coils were swapped out and weren't the problem.