can any one please please help i have changed the plugs. plug leads. distributer. and the dis/ cap. also changed the injectors but my primera sri p10 still only running on 3 cyl also had a compresion test and a new
petrol filter so i am at a loss

HI, Missfires can be caused by a few things. Ok lets start here.
where all the compressions the same on all cylinders, and whot readings?

do you know which cylinder the missfire is on?

Are all the injectors clicking while the engine is running, (can be checked by placing a screwdriver end on the injector and putting the handle on your ear)

With all the parts you have replaced i would be inclined to check the inlet manifold for air leaks.
This is very simple to do. Get yourself a can of WD40, start the car and spray the WD40 around the manifold. Make sure you spray all of it and dont forget to spray the manifold to head gasket also. if you have a air leak the WD40 will be drawn into the engine, thus the engine note will change, allowing you to find the leak.

keep me posted on what you find.

regards