Cutting out while moving

Hi !
Having problems with my Peugeot 206
Has now taken to cutting out on starting/ low rev moving
Intermittent fault..can also lock steering sometimes.
Also since changing indicator bulb seems to be showing passenger airbag disabled..understand faulty indicator unit can cause this..so I'm wondering as its the same side.
For yr info to date have changed following.
Cam belt. Catalytic conv.coil pack. Spark plugs.lambda sensors x 2 . Starter motor.
Like Johny Cash says..I'm building it one part at a time !
Think may be sending petrol through Cat too.
Horn also packed up.Car been showing engine management light although been in garage reguarly ?
Despite all...I still love my Peugeot. .but then I am crazy.
Any help gratefully rec.
Many thanks...