450 door latch / engine miss intermittent

1. I have a 1979 450SL that has a door latch problem. The door will open from the inside but will not open from the outside. (drivers door) I have removed the outside handle and all looks in order. Seems like something is going on down at the door latch itself. Any suggestions would be appreciated.

2. The engine has an intermittent miss that feels like a "fish nibbling on your line" (for those who dont fish it is a tug back and forth, not real hard just back and forth) It does this at all speeds and also misses at idle. It will seem to clear up and then start again. I had thought maybe bad fuel or a vacum leak but someone suggested plug wire ends(I guess common problem) or plugs. Maybe a complete ignition tune up is in order. Any help would be greatly appreciated.

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