Hi Rehan and all well i was lucky enough to get my hands on (through my mechanic) a computer scanner that showed the knock sensor #1 (there are two per 3 cylinders) had failed 271 times.At first my car (started 6 monts ago with 90,000K on 98 v6) to just die while driving or just sitting.
The mech thought first the cam postion sensors.this car as all modern cars have many sensors (all bosch) that report back to computer any changes in voltage,in my case i replaced the cam sensor directly under throttle intake at aa cost of $80 US,it was a simple ten minute job,so since these are known to fail,i did it as process of elimination,well didn't cure stalling.The car goes into s "safe mode" when it senses anything wrong with the knock sensor and shuts off.Well after turning the key on it runs perfect for a week or less and then agin stalls,So after scanner told me one knock sensor bad i ordered both at a cost of $80 each.But when he tried to get to thme they were buried down beneath the intake shiny chrome pies and manifold etc.If you look at your v6 and at far top left of engine you will see a black think wire attached to top of engine with a white plug.at other side there is one with a black plug,this is sensor #1.Now imagine follow the wire down to where it may connect to engine block.You will see no way in hell to get at it with less than 12 hours time,Even the engine mount had to be loosened to allow the black water tube (it cools the engine top) that runs to the water thermostat housing.I am not kidding all other sensors are easy to get to theses are a mess,in design! Alfa really screwed up on this one.He tells me on the jap subaru it is on top and takes an hour.So there you have it.if car stalls and it isn't the mass air flow sensor (easily checked by idling car and gently tapping the side of plug in to air flow sensor and it is bad ,brokedn etc. it will be noticible by stalling etc.) Then try the 02 sensor that should be change as a servicible item at 50,000k anyway then suspect either of the 2 knock sensors.as for porting,it is obvious you fellows aren't into american hot rods etc.It is a standard thing to do to remove the chrome intakes and take off the intake runners that are bolted directly under them (these had to be removed to get to knocks anyway) and the mechanic takes a fine buffing steel bruch attached to a drill ot by hand and start to smooth out all the inside of the runners that are always rough cast inside from the factory.The mech tells me only Porsche and Ferarri is done from factory.By enlarging and polishing smooth the inside of all 6 intake tubes you get a clean uniterupted flow of gases.You have no idea what a dif this makes in horsepower and throttle response.It is simply the biggest and easiest (anyone can do it)performance mod that is i think better than the lowly 6 or 8 horses form chipping for 5 times the cost.Thanks for asking.By the way with 90,000k on the car the mech looked at the top of pistons,vales and said it was spotless.Good gas Mobil1 syn and high revs keep that way.Alfa makes a very reliable engine here.