Re: 2.5 v6 trying to cut out.i think
With my V6 the suspects would be:
(In no order)
1) Battery - the V6 is really reliant on the battery being in good nick, if it is dying, then your engine will soon start to be rough!
2) Spark plugs - they have a long life span, but can start to die
3) Coil packs - also have a long life span - search the forum for how to tell if they are dying
4) Air leak - check to see if the bend plastic pipe work from your airfilter to the throttle body has loads of holes in it where it has perished or split.
5) Is the throttle butterfy all gooed up with black crap? It takes seconds to take of the big hose and gently clean it with a rag.
6) Is the airfilter old/dirt/blocked?
Main contenders for the culprit:
1) MAF sensor - this is located just above the airfilter. You can unplug it and see if your car starts idling normally again. If it does, time for a new MAF and avoid ebay versions like the plague. Expensive to buy but cheap to instal.
2) ECU gremlin - disconnect the battery over night - reconnect again and see where the land lies. That simple!
3) Exhaust blocked - this is what happened to mine. The cat convertor broke up inside and started to block the exhaust, causing a very weak idle and then major engine running problems. Very easy to fix, but took ages to diagnose!
4) Possible the fly by wire system your car has where there is a sensor on the throttle pedal that talks to the motor controlled throttle body on the engine - the connectors can break, get dirty, need tinkering with, or the potentiometers themselves can need replacing.
Some people may tell you it is the fuel pump or fuel filter that is blocked - on your 156 the pump has its own intergral filter and the whole unit is located in the fuel tank and is very very very unlikely to fail or to be the item at fault here.
Hope this helps! Use the search function for more help on dodgy spark plugs/coil packs/ air trunking/ airfilter/ MAF/throttle pedal position sensor/ issues.