Hi there, I own a 2002 Peugeot 307 2.0 XSI.

From about a year back the engine started showing some odd behaviour!

When the engine is idle (not immediately after I turn it on) at about 700RPM
and even with AC turned off, the engine seems to lose RPMs in a fraction of
a second a the electronic has to "catch up" by pulling the engine a little
bit (I believe it is called bliping the engine).
In other words I am at stand still (in neutral with manual gearbox), with
engine at idle at about 700rpm and from very frequent intervals of time, the
rotations drop to 600rpm and the engine automaticly blips the throttle a bit
to about 750rpm which makes the rotations drop smoothly and quickly back to
the "neutral" 700rpm.

I've noticed that when I turn the AC on, as the compressor kicks in, the
engine is forced to run at about 800rpm (as the extra force is needed to
activate the AC) and the engine doesn't produce this behaviour, at least
noticeably.
Also when the ignition is turned on, the car starts at a idle of 1000rpm and
then drops in stages to 900rpm, 800rpm and finally 650-700rpm (normal idle)
until it gets warm enough.
The sound of the engine is as the idle is irregular as if there it isn't
properly calibrated idle point (in old carburator cars the sound is about
the same).

Also this hapens in hot or cold weather, any range of normal engine
operating temperature (85-95 ºC).
I've went to the dealer but they are completly morons and as allways are
never able to sort anything out! They told me I needed to clean the
injectors of residue (normal when operating for many years) and so they
proceed, but it still hapens to me.

Any thoughts??

Best whishes and tkx in advance