I would be carefully looks can be deceiving they may look the same but the internals eg plunger, cup, metering body etc may be different if you thing you have bad injector simple and low tech way of finding it am not sure what the exhaust on a td4 is like but if you have a laser temp gun let the engine idle for 10 mins and go along each cylinder on exhaust with temp gun if you have a injector over fuelling it will be a lot hotter if you got one not firing or partially firing you will have a cold cylinder 20 degrees variance is fine