There's been some chatter about removing the intake manifold to correct vacuum leaks so I though I'd bring you all up to speed on my current ongoing experience with this process on an 89 S4.

I had a hesitation at low RPM under acceleration which was most likely a vacuum leak in a breather or other hose so I decided to pull the manifold using the instructions posted By Dave Chamberlain on the Owners Club website.
How to remove the intake? intake1b.pdf  (courtesy http://928oc.org/journal/intake1b.pdf )

Dave, the beer is on me!

Don't even begin to try this job until you read and understand these instructions!! They tell you about things not covered in the manuals like
hidden connectors etc and are straightforward & comprehensive. So off we go:

PHASE I-Disassembly

Started by disconnecting a bunch of things as directed. I soon discover that heat and time have turned all of the male connectors on the knock sensor harnesses into crumbly bits of black powder. They were basically held together by the spring force of the contacts.

The fuel rails were covered with a brown foam insulation that turned to dust from the effects of time and temp when you touched it I ended up pulling all of this off and blowing the bits and pieces out of the engine nooks with compressed air BEFORE I took out the injectors. Thus very little of it fell into the engine through the injector holes. The injector harness and other wires are attached to the fuel rails with round plastic wire clamps that also shatter into little plastic bits and fall down into the engine V when you try to remove them. Try and remove all of this before removing the injectors.
 
Removing the injectors from the manifold was a chore! I found I needed to loosen the brackets holding all the fuel dampers and swing them out of the way so the ends of the rail were free, remove the clips holding the rail to the top of the injectors, and then lift off the rail to leave each inject in the manifold. Use parts cleaner or WD 40 to flush the gunk out of the hole in the manifold and then pull and tug and curse and swear and bitch 8 times until the bleeding things come out! You are only on page 3-4 of the instructions so far.
 
OK so everything is going according to plan (and the instructions) until it came time to unhook the injectors from the wiring harness. I did not buy the special Bosch tool referenced in the instructions. Bad idea! These connectors have 2 small wires molded into the male end that interlock with the female end for a secure connection. Even after I pushed those wires aside-no easy task-needed little jewelers screwdrivers and bits of piano wire- I still couldn't separate the injector from the harness. The effects of heat and time (again) have fused them together. I ended up leaving them all connected but removed them from the manifold-bagged them for protection & pushed them to the side. Monday I went to the dealer-3 blocks from work-and ordered the $20.00 tool. It still hadn't arrived 8 days later and then they told me it's back ordered till sometime later this month. I have one ordered from DR!

The rest of the removal was straightforward until I came to the part that said.. using the special tool remove the connector from the idle stabilizer valve/motor located under the manifold body. Oh. So that's what that little hole is for in the top of the manifold. You lay on top of the car, look through the hole shine a light from the firewall and there is the connector.
But wait, the rubber elbow connecting the MAF sensor to the throttle body blocks your hand from even getting in their. Take that off! And even if I had the tool, when you put you hand in to gap the connector, you block the light and it goes dark under there. Remove hand...see connector...insert hand... no see connector...repeat until insanity ensues. I used a very long thin screw driver to pry off the locking wire and I still couldn't get the connector off. Same problem as with the injectors. I just left it connected and continued on. The rest wasn't bad and I had the manifold free rather  shortly. I flipped it on its side and could then reach in, got a better grip and disconnected this connector and it came off cleanly.
PHASE II-Inspection

The top of the engine is a wide flat shelf and was filled with a slew of dirty bits and pieces of stuff and such including a 10mm socket and was also covered with about 1/4" of pure clean Mobil 1 15w-50! One of the 3 hoses coming off the base of the oil filler neck has a hole in it 1/2" long and about 1/4" wide. Also, the gasket at the base of the oil filler neck itself was shot. I could rock the neck back & forth and see oils oil ooze out of the joint. That could explain my high oil consumption. Further inspection revealed that the wire insulation and plastic housings of both knock sensors were totally destroyed by heat & vibration. The connector for the Hall effect/ignition timing sensor mounted above the flywheel was cracked and came apart in my hand when I touched it. It's amazing this car even ran! Cleaned out the oil and gunk here and that had accumulated on the walls of the intake ports in the head. Amazing amounts of oily crud & goo.

Let's look at the manifold. The paint is flaking off of it all over so I think I'd like to get it refinished. Pop off the side pieces- no problem.
Separate the top and bottom halves -no problem. Poke the idle stabilizer valve. It moves. Not good. The little rubber stud mounts attaching it to the manifold are shot. Check my flappy actuator-works fine-take it apart and out. Uh Oh. How am I going to get this refinished with any sort of dipped/immersion coating process with these nice little roller bearings for the flappy shaft pressed into the manifold? How will I get them out? Can I get replacements? I don't know. Do any of you?? Until I figure this out I'm stymied. Is there anyway I can refinish the manifold with these installed?? Help Help Help!!

Phase III-TBD

P. McGinnis