hi i have a 2009 fabia 2 1.6 16v petrol that idles around 550/600 rpm when warm but noticed when im stopped in traffic sometimes the revs drop for a few seconds and it feels like its about to stall any ideas only had the car two weeks and have already taken it back to the garage once for tapping on cold mornings (hydraulic lifter valves clogged )

36 minutes ago, evans82 said:

hi i have a 2009 fabia 2 1.6 16v petrol that idles around 550/600 rpm when warm but noticed when im stopped in traffic sometimes the revs drop for a few seconds and it feels like its about to stall any ideas only had the car two weeks and have already taken it back to the garage once for tapping on cold mornings (hydraulic lifter valves clogged )

Do any of the interior lights dim? Sometimes, a sudden strain on the battery and alternator can cause a slight drop in rpms, but usually only just perceptible, not like how you describe yours to be. 

Any strange noises from fuel pump?

I have the interior lights off at the moment because I have another fault with the door shut sensor thinking the door is open all the time supposed to getting that fixed on Monday under warranty. Not sure about the fuel pump I'm pretty much a novice when it comes to cars. I did wonder if it could be spark plugs or the ignition coils.