Golf IV / Jetta IV :: VW 1.6 SR (AKL Engine) Rough Running / High Fuel Consumption

Regarding my problem (outline below):

>> Went for a refueling stop, and thereafter proceeded onto the highway

>> Approx. 500m into the drive onto the highway the car started jerking and running rough with an initial puff of smoke (none thereafter)

>> Immediately after this initial jerking/shuddering there was a significant increase in fuel consumption i.e. from a familiar 8.2L/100km to 18L/100km in the cruise

>> We continued driving not knowing what it was (I suspected a spark plug may have stopped working)

>> Pulled up at the gas station to observe what went wrong inside the engine bay - no signs of any leaks, fuel sprays, etc. but only that the engine was shaking

>> I checked the rear of the car while the car was idling and observed a pulsating sound...some light smoke and a fuel-rich egg-like smell

>> Asked around and I was led to think the catalytic converter was ruined, so the next day I had the catalytic converter cut out

>> After removing the catalytic converter the problem persisted...although the engine operated with slightly less flow resistance

Attempt at diagnosing the problem

>> My wife called in a technician from BMW at Canal Walk to come have a look and what errors were flagged

>> The tech ran the diagnostic and no fault codes were indicated, except a few short circuit faults due to my incorrectly placing -ve on +ve when I tried to charge my cars battery with jumper cables

>> He proceeded to ask if we changed the spark plugs, I said yes. He then looked at the oil on the intake manifold and said there could be a torn valve on the intake manifold and that air that is not measured by the air mass flow sensor is entering the engine, which is causing the car to rev hunt (this problem of rev hunting has been with us for a while). The engine also shuts down uncommanded at stops and sometimes between shifting gears with the subsequent loss of power steering (very dangerous!!)

>> We also had the O2 sensor replaced a month before this occurence

The images attached (#1- #3) are marked up to indicate the component I am referring to.

[IMG] FilesImage_1.jpg[/IMG]

[IMG] FilesImage_2.jpg[/IMG]

[IMG] FilesImage_3.jpg[/IMG]

Went to Cape City VW in Cape Town and the part number for that orange thing/diaphragm is 06A 198 205A 'Repair kit for valve'. Is this significant? The car sounds as strange at idle...as if has noisy valves. I can upload (if there is an option) a sound clip of how the car sounds if this assists.