Mercedes Benz repair: 87 Merc 420sel, spray mist bottle, tyen

Question
i got a 420sel for my girlfriend, lately shes been having issues keeping it running, from time to time when she would go to take off from a long stop the car would die, sometime even when she came to a stop it would. to me it seems to run a tad rough at idle, but when i drive it i can keep it running by "two footing" it (foot on brake and one on gas giving it just a touch of gas) is it just a tune up needed? the cap, rotor, plugs, and wires all look good to me, but i did find one plug (#4) lose in its hole.

Answer
it probably needs a tune upstart with the plugs then do the cap and rotor tyen retime the engine then take it from there if your worried about the plugs get a spray mist bottle and spray around the plugs and see if it kills or dies your tach shouldread 750 at nuetral