SUBARU CYLINDER MISFIRE

1998 SUBARU FORESTER PO301,PO302,PO303,PO304 in sequence but not all at once. Idle is slightly rough. Cold engine "bucks" under acceleration. Warm engine has slight hesitation under acceleration. Cylinder misfire codes come only occasionally at either idle or highway speed. 2.5l dohc,Manual trans,195k. Have tried new plugs(platinum)previous plugs looked white(lean)but not blistered,wires,coilpack,throttle body,tps,egr,injectors,pcv,intake manifold and gaskets. Intake vaccuum is 15 hg,seems low, i dont know squat about subarus and i cant find a book for a 98. sometimes it will run smooth as silk for the rest of a drive and then act up at a stop sign (rough idle) The head gaskets have been replaced with the updated ones, they are holding up fine. Fuel pressure is 35 psi with engine off. 30 with engine running. 39 with engine running and vaccuum hose disconnected from fuel pressure regulator. anyone know manifold vac and fuel press. for this subie ?

I dont have a clear answer for you, but one guy on these blog pages seem to always say to put in OE wires and plugs. My suggestion would be go to the library and get a repair manual, "one of thoes 3 inch thick books" they have all the tech. numbers your looking for.

Good Luck to you.

Hello everyone, I found fuel pressure specs 43.5 psi. Replaced replaced pump and regulator runs like new.