I've had problems recently with My focus (82K on the clock). Coming back round the M25 it struggled to accelerate barely getting over 60mph. A mobile mechanic diagnosed a leaking injector which I had replaced. But the car still suffers from lack of acceleration power, struggling to get up hills at times. A local garage with a good reputation says the turbo has failed and quoted £800 to repair. However someone else has said it's a common problem for an injector to be blocked and all I need is to put some injector cleaner through and then 'thrash the engine' until it blows away the blockage. Has anyone else had this problem or know what it could be?