Another thing I would say is that any of the Renault models that my customers have bought have been advised by myself to have the crank sensor and wiring replaced even if there is no problem at present. I have carried out this work on at least 30 odd Renault models. Also bad engine earths and body earths can causes strange problems. Most crank sensor failures I have seen on these are when the engine is hot but have had a couple that fail from cold. Also check for fretting on the connector terminals as I had a Vivaro last week with the Renault 1.9DCi cutting out and that was the fault. You could see where the connecting points of the terminals had worn away. Don't bother with any of the aftermarket crank sensors that will probably plug into your existing wiring as you'll never know where you are then. Ideally you would like to catch this failing on a scope to prove the failed component but I'd be inclined to recommend having the crank sensor and wiring mod done even if it's not the problem at the moment. Is this the 1.6 engine with the dephaser pulley problems?

Liam