Hi Chris
The spots of Diesel bit is a common problem, due to worn O rings in the fuel pump assembly. See this post to fix it:
Replacing Fuel pump seals (with pics)
As far as noise goes, thats a difficult one, but check the following:
1. The big black plastic engine undershield is present and not flapping about. Just look under the van and if you can see the underside of your engine the undershield is missing! It makes quite a difference noise-wise.
2. The heatshield on the exhaust manifold is intact and not all bolts are tight.
3. The big black plastic air pipe is tightly connected to the metal curved junction on the end of the inlet manifold (lift drivers seat then look upper right and back a bit).......there is also a small rubber pipe which runs from this junction to the fuel pump.this should be tightly connected too. If either of these are loose you would get 'sucky' noises and a marked sluggishness.
4. Follow the air flow route from black plastic intake under bonnet, (top )left) to air filter (under drivers seat), then around the back of cylinder head to turbo (under passenger seat) then down and to the bottom front (intercooler) then back up to the inlet manifold joint mentioned above.
Check all joints are tight....lid of filter casing is correctly fastened, and filter is present.
5. Check all exhaust joints.
6. Check drive belt tightness
7. Valve clearances may not be set properly which will give a taxi-like rattle most noticeable at low revs.
8.The test for faulty injectors is to slightly slacken them off one by one (being very careful to avoid high pressure diesel spray, especially protect eyes)....you should notice distinct engine note change when they're slackened slightly like a misfire.......if there is no change to engine noise then there is probably a problem with that injector. If you do this test be very careful not damage the fuel return pipe (the curly pipe which links each injector).
9. Check the egr pipework (metal pipes running around the back of cylinder head from exhaust to inlet manifold), check all connections are tight.
Generally it's fair to say the Bongo is quite noisy on tickover but not as soon as revs are lifted a little. However they do all vary, I've just changed my engine and the replacement engine which has done 132,000km's, is much quieter than the old one.
Oh you may also like to try disabling the egr (exhaust gas recirculation) system, as mine seemed to quieten a bit when i did this, you'll notice a smoother and more responsive drive too. There are various methods of doing this, just do a search for 'egr' and resaearch the subject a bit.
If all else fails try going out without the wife.....it might be this simple!
Good luck
Rob