I have a 2003 Renault Clio 1.5 DCi with 70,000 miles. When starting from cold, the engine turns and fires but does not pick up. On the third attempt the engine starts and runs slowly. It hunts, and after approximately five seconds it gradually picks up to normal tickover. This has been going on for some time. It starts ok for the rest of the day and performs normally, but the problem returns if it stands for 10 hours or more. I have made long journeys, including 80 miles towing, and short journeys during this period.

Last week it passed its MoT including the emissions test. I have changed and checked all heater plugs, changed the fuel filter, replaced the leak-off pipes from the injectors, and all other pipes look in good condition. I have found that it helps if I pump the accelerator three times before initially engaging the starter, but it still starts slowly. My local garage has put it on diagnostics equipment but has not been able to identify any cause. Do you have any suggestions?