D15B7 shaking on low rpms
 

Hi to all. I have 95 civic 4dr with d15b7 on it. A few days ago the engine started shaking between 1000-3000 rpm but only when get warmed, when is still cold runs great. Today i took out the spark wires and the holes for the spark plugs were all in oil, which means i need new valve cover gasket, now is with silicone on it and obviously is bad. I bought new 4 spark plugs NJK-R and replaced the old ones, but no success. So where i should to look up for a problem, wires, coil, distributor, lambda sensor and etc. There are so many things who could be the reason for this so every help and advices are appreciate.

could be the injectors try adding some Seafoam injector cleaner and se if that helps. also clean out your IACV.