Just back from having done the London to Brighton run and the car started to not want to tick over but rather cut out. Always started with a flick of the key but a right royal pain. The car behaved impeccably until the second leg and about 65 miles into the day. Runs like a dream but doesn't want to idle and what with the traffic into Brighton today it made for careful throttle control through a whole mass of traffic.Always runs fine on shorter journeys and has only recently started this new phenomenen. I have checked the coolant level as I believe that the idle may be controlled off the back of the coolant system. Hoses all look ok and then again they will as the car runs fine until it gets hot. Engine temperature stays rock solid as it should with the new Passat radiator etc. A bit bemused as I cannot find anything obvious.

Any bright ideas out there please?

First thought would be head gasket but if it runs ok cold and not lost any power or coolant will not be that. Could be throttle pot as water temp sensor will give cold fuel enrichment but this drops back as it reaches temperature. Check resistance of water temp sensor and air inlet temp sensor. Not sure if these engines have a mass airflow meter but usually run like a bears bottom if not working
Ian

A couple of other things to check, HT leads - the ones that were on my VVC engine were shot (assuming you are the 143 with the coil packs on the block rather than the later mems3.0 with the coils on the cam cover)
Is the exhaust sooty? if so could be the lambda. These do go too. When mine went it still ran okay but very rich and lots of sooting up could give a misfire/poor idle.

Engine had a full top end rebuild last year so know that is right and dandy. Will have a look at your suggestion. Runs like a dream with rock steady temperature and then suddenly starts the dreaded cutting out in traffic. Turn it off and have a quick lunch and start again - all back fine again.

Thanks I will,replace the HT leads and the sensor amd see how that goes too.

Grateful for all the sound advice

Check battery is still good 1st.

SAS

Found the problem, the inlet manifold pipe to the idle control valve knackered. A bodge up repair has been done to get by but does anyone know the best place to get a new one please?

Thanks

http://www.ebay.co.uk/itm/MGF-1-8-16v-K-SERIES-IDLE-CONTROL-VALVE-PIPE-/131848787584?hash=item1eb2ccd680:g:TmoAAOSwgQ9Vomi7

Like this? There are some new ones for £14 too.

If its the same on the 1.6 plastic inlet manifold I might have one in my shed - I'll look next time I'm out there...

I think Sanzo is clearing out his shed
John