how is the fuel pressure?

I'd replace the valve cover gasket around the spark holes like you said and see if that helps the oil problem. Are they old?

Another thing you might want to try is swapping out the ECU for a known good one. You must have one laying around with all of your B18B's. Probably won't help the bucking problem, but if you have one laying around it may be worth a shot.

Also, how does the intake manifold look? Could it possibly have some build up in it? Maybe try running some seafoam through it.