car shaking at idle

[highboy_coupe]

Hi all, I have been driving my '98 318ti for arounf 7 months and cannot get rid of what feels like a misfire at idle. I have read hundreds of posts on various forums but nothing ever seems to get resolved. If you put your ear to the tailpipe then you can hear a random 'boof' sound every 5-10 seconds.
Is this really just that the M44 engine has a rough idle?

I have no CEL on.
If I unplug the MAF then nothing changes ( I have cleaned it too).
If I unplug the ICV the idle gets a little worse, kind of uneven.
If I unplug the TPS then the car dies.
If I take of the oil cap the idle gets a little worse, more shakey.
Spraying alchahol around the intake boot does not raise the idle.

I have replaced the ICV with a recon unit, and cleaned it, replaced the PCV and hoses, fuel filter, coil pack and plugs. It has NGK oem plugs now.
Flushed out coolant and replaced with BMW blue, replaced Tstat and water pump, had block test and negative for hydrocarbons.

Thanks for any help.

[cooljess76]

This is a shot in the dark here, but if you remove your valve cover and locate the vent towards the back where the CCV hose attaches to the cover, it somethimes gets clogged up with gunk. It's just a little port on the back of the valve cover, but when it gets clogged it can cause a rough idle.

[roy23pim]

check for vacuum leaks .. check the intake manifold gaskets .. you could also have a cylinder misfiring .. oh n check that there are no restrictions in your exhaust .. for example the catalytic converter it may be clogged thats maybe why you hear that "boof" from the exhaust...

[applefan]

check out this post.

http://www.318ti.org/forum/showthread.php?t=27237
my car had a rough idle for a long time. Finally the CCVV( some call it PCV) failed completely creating a very confusing sound.

I repleaced the CCVV with a new one and all went well. as a bonus, the rough idel went away also.

[drrty byl]

Have you checked the injector vacuum feeds underneath the upper intake manifold for cracks?