Thought I'd cap this post. I took it in yesterday. It was indeed the plug wires - my original uneducated guess. I'm assuming when the cap, rotor and plugs were changed the wires got bent and a couple went bad. It idid work fine for a couple of days but I'm sure if they were near the edge a few dozen bumps over Manhattan's finest pavement did them in. I should hav ethem installed by this afternoon. Hopefully you won't hear from me on this thread again because that will mean I finally solved the problem.
Thank for all the help.
'88 560SL Pearl Black/Java 152K
'94 E320 Anthracite/Grey 89K
'94 E420 Black/Bamboo
'71 280SEL 4.5