Can any one... Explain me ... how to do ... (Few Tuning Issues...)

Hi, Greeting to All Experts,
Well, I have posted a message with the subject, what could be the problem & what to replace. I got replies from Mr. LAmbach & Mr. Tiger
thanks for that. as part of continuation
I would like to know these following thing to get tune my MB to get more consumption & to rectify other issues. (please explain me in deatail)
My car details as follows:- 260 MB, 6 cylinders, 2.6 Liter engine, Auto transmission, Model 91
1.) How to adjust the Engine Valve?
2.) How to adjust the Distributor (timing)? (fixed)
3.) IF fuel accumulator is not working as suppose to be, will it cause to have any vibration?
4.) If valve seals allow engine oil to be sucked in to engine all the time, there will be having any vibration? Or in the morning with first start only?
5.) If cause of spark plug cable is poor ignition to spark plug, this can be a reason to more fuel consumption?
Once again thanks for all
All your comments & advices & recommendations are appreciated
have a good day
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