just done the head gaskets on my wrx 93 and it only seems to be running o n 3 cylinders but every now and again it will run on all four and its doing my head in tryed new coil pack injector and plug but still the same

 

I would start by doing a compression test to check the 'internal health' of the engine.
It might be a hydraulic lifter not being able to pump back up after they have been out ( assume you stripped and cleaned the lifters before re-assembly).

Mick

 

i'd second that,, not much eles really seen as you've done the most known problem solves there. cylinder down on compression?

wayne.

 

Was correct thickness of gasket used for comp ratio...

 

going to do compression test in morning and as for lifters i was thinking the same thing myself but how could i solve this

 

well not got around to doing compression today but noticed that car has been runing fine most of the day and only runs on 3 every now and again but when its running on 3 and i give it a couple of revs it seems to come back to life for a bit