Hey folks, im looking for some insight.

So long story short ive been working on my friends project 91 300e. He wanted to get a summer car that he could learn about cars on, and I could show him how the mystery of automobiles work.lol. He has always like my collection of older Benzes, and wanted to get one himself. So over the winter we picked up a decent shape 91 300e with the m103, and have been slowly working away at it, getting it back into tip top shape.
I have done a once over thru the fuel injection system, and got all the linkages and sensors adjusted and working properly. Fixed a small fuel leak, fixed the central locking, and got the hvac working with a new regulator.

Anyways, heres where I got a question. So im in the process of replacing all the plugs, wires, dist cap, and rotor. (about to order them). Yet im still having a hell of a time with the car. I found a mb invoice for a new head gasket and bolts in the glove box from a few years ago. So that's good news. However, im wondering if whoever did the work could of screwed up the valve timing by a few degrees retarded. Problem I am having is, when I go to start up the car to move it out of the shop after sitting. It has one hell of a time starting. It will sputter, backfire, and try to kick back on the starter.
After a bit of throttle persuasion. it will stumble some more. then slowly come to life, and run perfectly fine.
I tried to use the timing light and see how things were, but I couldn't read the marks crank marks from the top of the engine while running. (obviously I know that the ignition timing is independent of the cam phase, but it was worth a check)

Once I get new plugs, wires, etc. Hopefully this will be eliminated. However, I wanted to get some insight on the possibility that someone who did the head work, put the valve timing out of sync. And/or the valve clearance is out of wack. (does the cam sprocket slip onto the cam in more then one position)
I read this:
http://www.w124performance.com/service/w124CD1/Program/Engine/103/05-2150.pdf
And im still a bit un clear on how to adjust the valve clearance. Pics ive seen shows that this engine has no adjustments on the rockers (assuming hydraulic lifers like on the m117/116 that im used to), yet this pic shows something that allows valve adjustment.....

I haven't lifted the valve cover yet, but I just want to be aware of what to inspect.

I have a feeling, a refresh on the ignition components will help. But yea never know with these old benzes.
Thanks

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Just my MB's:
1990 420sel - Winter DD - 410,000km
1990 560sel - absolutely showroom mint - 360,000km!