Rb20 Injector Issue, Maybe?

[Tonks]

Ok so im running an rb20 with gtr injectors everything was sweet till the car started playing up a few weeks ago, pulled plugs, coilpacks all that stuff. Pulled injectors and got em tested turned out to be #4 injector was shit so swapped with a mates spare one and car was all good after that.

Anyway got my new injector from nissan and finally got round to fitting it tonight. Did the usual checks after fitting it. Primed it all checked for leaks and was all good. Took it for a drive afterwards to check it all. The problem I had was that under load it sort of stutters, hard to explain but roll onto the accelerator it will accelerate slowly and stutter for a second or two then out of nowhere it just picks up pulls like normal. Tanks at half and I put half a thing of injector cleaner in it. It said it treats 55L so only reason I put half in. Would it be because its a new injector and hasn't had much fuel through it or should they be sweet straight outta the box? I haven't delt to much with them before?

Is it just a matter of putting more kays on it? Or does it sound like I have other issues. Double checked all lines I took off, crossover pipe etc as well.

Thanks for any help.