I have a 1996 C220 and it just started having this idling problem. It starts up fine, but the RPMs drop off everytime I take my foot off the gas. I went and changed hte fuse for electrical components, which was a temporary fix because once I try to shift into drive or reverse, it blows the fuse and the RPMs drop off again and the engine cuts off. I recently got it out of the shop last week and they replaced the fuel pump, fuel filter, relay, and electric ignition switch. Any ideas??

 

1. Air filter clogged,
2. Vacuum leak at the throttle body, inlet manifold or associated hoses,
3. Worn, faulty or incorrectly gapped spark plugs,
4. Uneven or low cylinder compressions
5. Camshaft lobes worn,
6. Timing chain incorrectly fitted,
7. Blocked fuel injector.