My ERST has started running on 3 cylinders, it idles fine and runs on 4, but with throttle it runs on 3 ive replaced leads, plugs, dizzy cap, rotor arm and fuel filter, done a compression test and that's fine, any help much appreciated

 

wat compression is it

 

could be coil breaking up under load mate

 

it also tends to do this if u have a badly worn tappett

 

Cheers for the replys the compression is ok about 120 across

 

that is a little low m8 but not too tragic

 

Is it number 4 thats missing?