Peugeot 406LX1.8 ltr petrol 1997 fuel fault?

My car is fine when it is cold run like a dream,but when it approaches 70c it starts to cut out and hunt it's very difficult to keep running or pull away from lights with out it lurching or cutting or stalling if i persist with it and it reaches 80c or more it settles down temperature settles at 70c for rest of trip CAN YOU Please help.