saxbyt

Hi, I recently bought a 2007 1.8TDCi Galaxy with 71,000m on the clock from a private seller. It was in A1 condition with full main dealer service history to 63k. I've driven it without problem for 2 weeks but today I had six adults in the car and went up a hill at about 40-50mph and as I accelerated it hesitated. Tried several times after that, putting my foot down at about 60 on the flat etc., and again hesitation like a fuel blockage. Also tried without the passengers. Absolutely no problems otherwise, it cruises along at 60 or above smoothly only if I put my foot down above about 50 does it do this, almost as if it cant get enough fuel when the load is high. My guess is a blocked fuel filter but any other ideas please. I'm guessing this isn't a DIY job either! I have a local garage that has always been really good and I'd like to give them the business of fixing it but they don't do a lot of fords to my knowledge (BMWs etc) so am wondering if a main dealer is the answer in this case, but of course am wary of the potential costs. Many thanks in advance for any help