how would i go about making a vanilla mob drop items every (for example) ten minuites without it having to die?

you could use LivingUpdateEvent and NBT of an entity (as a counter) to achieve this .

okeeeeey, so i did this

@ForgeSubscribe
                  public void onEntityDrop(LivingUpdateEvent event) {
                               rand = Math.random();
                                if (event.entityLiving instanceof EntityCow) {
                                     //The integer at the end relates to how many Items will be dropped(percentage). 
                                     if (rand < 0.75d){
                                        //The integer at the end relates to how many Items will be dropped(amount). 
                                        event.entityLiving.dropItem(ashtonsmod.Manure.shiftedIndex, 1);

                                   }
                             }

now whenever i spawn a cow it spawns thousand of items continuousely??? heeeeeelp before i drown in poop!