I have an '84 190E that my father bought new and stored in the garage for 10 years. Total mileage=80k now, after I have had it for close to two years. My dad claims this problem has occured since new. It was the first 5spd in Oregon and when I depress the clutch and as though i were to put it in neutral, the engine drops to around 300 rpms, shudders bad, then comes back up. This happens virtually all the time, especially when driven harder or kept in gear until the car has slowed to around 1500 rpms. I have replaced the fuel pump relay as it went out, alternator, plugs, cap, belts, and also many tune ups. BTW, the problem is less occurant when the car is topped off to the brim with oil. No mb mechanic or dealer has found a fix yet and I'm tired of dropping money into it. I have seen a few rare people online who have the same problem, but no fix. Any ideas?