Looking for advice on a mondeo issue

I have a 2005 diesel mondeo TDCI which broke down recently. Got towed to the garage where it was found the diesel injector pump had gone. Got a new one fitted along with an easy r valve. Fuel tank was flushed and new fuel filter fitted. All calibration done and everything is up to date there. Injectors checked and all okay. The thing is, there is a problem the garage can't identify. The car starts in the morning but when trying to start it on a warm engine, sometimes it will and sometimes it won't. The engine turns over at low revs and the engine management light and the battery light come on. When it decides to start, it gives a little shudder and both lights go off. I've had two main dealers look at it and neither can identify the issue.

Has anybody ever come across this or would anybody have any suggestions?

Thanks