i had the same problem on a 2.0 mk3 petrol Mondeo 3 months ago just ignored what i knew was working and checked what was left on my list .as a matter of coarse i checked the plugs took them out as soon as it happened again the plugs were soaking wet with fuel its assumed that its caused by no spark or no fuel or bad plug leads its not it flooding due to a faulty clutch pedal switch which is meant to reduce the fuel going into the cylinders when you change gear so that you have a nice smooth easy gear change the brake light switch dose much the same . check the terminals mine were black coated i cleaned them up and the wiring plug. put a bit vasalene on them and the plunger and connected them back up did the same with the brake pedal switch. took it for a test run works the same as it did when it was new. i ran it for a week with out any re occurrence of the problem then i gave it a service plugs oil,and filter change , air filter change it runs like a dream. If you need a new switch check e bay much cheaper than dealers .what actually happens is the same volume of fuel is going into the cylinders when you change gear then when you put you foot down to accelerate you put more fuel into the cylinders flooding it the plugs cannot ignite the fuel so you get what appears to be a misfire leading you to believe that either fuel starvation or faulty plugs or leads if your car performs ok on the motor way then it has to be the changing gear that or slowing down and pulling away in the same gear that causes the splutter /misfire has to be one of the two switches. bear in mind that diesels don't have a throttle cable but an accelerator pedal position censer which send signals to the fuel pump via the PCM (the cars computer)which if its covered with any thing or out of position will cause the same problems fuel in the cat is also taboo it destroys it hence the smell of petrol .And white smoke in diesels its unburned fuel which is heated by the cat and produces white smoke just like the red arrows use . it may also be that some one has worked on the car and not put every thing back as it was ie the accelerator censer. not being in the exact position . i hope that i've been able to help some of you that have this problem , there will be some cars that have the same symptoms but the problem will be different and until i am able to see or hear the car or am told in great accurate detail i can offer no solution
Alex ex RAF mtd, July 2013
