I bought a Mondeo Zetec (tdci 140) in April. When I purchased the vehicle it had just under 12,000 miles on the clock. It was only registered to ford prior to purchase. At about 15,000 miles I noticed a problem when going up the gears and trying to accelerate. There was a brief pause before the car moved forward. Then, with the momentum of going up into a higher gear, it was like a sudden, noticeable thrust in acceleration. I took it to ford who couldn't find a fault. They told me to come back when the "engine malfunction light" came on. I carried on driving the car (still performing exactly the same) until about 18,000 miles when the light eventually came on. I took it back to fords who told me that the light indicated a deterioration in my oil and oil filter. They changed the oil and filter, which I paid for because this wasn't covered under warranty. I also paid for a pcm update, as I was told it needed one. A couple of hundred miles later the light came on again. This time I was told the computer behind the dashboard was showing a fault. Fords cleared the fault, and for about 1,000 miles the car drove really well. At about 20,000 miles the car reverted to driving as before. Only this time the hesitation was gone, but the thrust in acceleration has returned. In addition, when this thrust in acceleration comes, so too does the engine malfunction light. This thrust in acceleration causes the engine to reverberate slightly. When the car runs in this way I also notice that my mpg takes a noticeable hit also!! Please help!! I really don't know what to do.