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.