I am having exactly the same fault with my Clio 1.5 (106).
Did you have any luck finding what the problem was, i have taken it to the local garage, and a main dealer.
The diagnostic was coming up Fuel Pressure Regulation Fault, however none of them was able to give a confident accurate solution to fix it.
Renault just suggested fitting a new fuel pump which will cost in excess of £500, with no guarantee this will fix the problem.
Could anyone suggest anything, esp. the OP who has (hopefully) had his fixed now??