Rough running 450 sl
 

I have a 1980 450 sl which I just got about 4 months ago. I started it up today for the first time in about 3 weeks. It was idling rough, I figured it just needed to warm up a little, but it persisted even after a good drive. It's not just at idle when it's rough, but all the time. I had no problems previously, not even a hint.

Should I be looking at plugs, cap, rotor, wires, fuel filter? If so, which first. Where is the fuel filter located on these?

Oh yeah, after my drive, when I put it in the garage, I could smell a sort of burning smell that I previously didn't have. Couldn't pinpoint the smell for sure, but perhaps from the exhaust (not sure though because the smell that I smelled from the exhaust pipes may have been there before and I didn't notice it). And advice would be appreciated!

Thanks,