Hi there welcome and thank you for the question hope i can be of some assistance to your problem
Have you had a diagnoistic computer on the vehicle to read out any fault codes?
the garage tells me that nothing is showing on any faults code
no faults have shown up
also having email problems as my email was registerd the last time i used this sercive
would the old injectors have done any other damage before they were changed
I wouldn't have thought so it is very rear to see these injectors cause diesel knock, they was a common fault on the 2005 / 2006 built vehicles at the back of the fuel pump to the bottom is a solenoid now this solenoid is the fuel timing solenoid and what use to happen is the solenoid got water into it and would then stick which would cause the fuel timing to advance hence you would get diesel knock, lack of power due to the advance of the fueling and smoke due to the incorrect burning of the fuel so i suspect this is proberely your fault now these can be bought separate to a pump from your ford dealer or from your local diesel specialist, but before you have this replaced just get your mechanic to check the fuel pump timing just to make sure the timing is not out as again there was issues on the 2005 / 2006 models with the timing chain tensors failing and cussing the timing to jump.
Let me know how you get on