Vehicle wont start?

In desperate need of some help, I have a 55 plate Renault Traffic, 1.9 dci 100 which is in use every day, never a problem since new. Now it just turns over and wont fire although a quick squirt of easy start and away it goes, runs/drives fine, but wont restart unless it gets a quick squirt of easy start??? When the van is running it now occasionally cuts out only when driving uphill, leave it in gear, turn ignition off then back on and it is fine again? I also noticed that the STOP light occasionally flickers then goes off. These are the only symptoms/issues the van has. Your help would be greatly appreciated!