i doubt very much its the cam seals! far more likely to be the rocker cover and if you have already replaced the rocker cover gasket once then i recon the cover is warped and will NEVER seal again!!

i had this on my 2000 2l and in the end converted to a silvertop rocker cover as they're harder to warp and use a much thicker gasket which seals FAR better!! if you go this route make sure you get the bolt spacers and rubber seals with the rocker cover as they are fucking dear from ford!!!