How Can I stop a Nissan Tino Hurricane 2.2TD from missing?

Car misses when around 2000rpm I have taken it to a Nissan Garage paid 75 for diagnostic wase of time so far they have diagnosed the fault to EGR vlve, Swirl Valve and now 4 injectors - I had them all changed an the fault stll persists .
Sometimes you can put your foot down and theres nothing there an drivin in built up area is like driving over cobbles.
So far it has cost 1600 quid the car is a 52 plate.
Im a low income family with Twins. Cant aford to keep wasting cash. Please can you help