SPUTTER and Hesitation

[Mr.Billyd]

Hello,
I have a 97 E300D
I had all my plastic lines changed at about 75K with factory orings
It's now about 2 years later and I am now at 103K.
I can see air in the line that goes from the main filter to the shut off. The car hesitates a bit and sputters some times. I just got my viton oring kit from Fryer power. The lines are not clear like new, but not too bad. If I go and change all my orings over to viton, could I do it without ordering all new lines? Am I asking for trouble by not changing them?
I plan on changing all of the orings on the low pressure side of the IP. I will change the orings DV later (HP side), as they look spot less. I also got a new main filter and prefilter. Are there any things I should look out for when changing filters, or the orings on the plastic lines going into the filter? Also, when I am in there, is there a test I can do on the GLOW plugs. They were changed at 60K. The car starts perfect. The last thing I want to do is go ripping the intake off again a few weeks later.
My IP is also leaking oil from the side cover. I got the new 20$ o-ring from MB. I can't seem to locate the Torq spec for these 6 bolts on the side cover.
What is the torq spec of the hold down plate for the lines coming out of the filter? Is there a DIY write up on this topic?

Thanks
Bill