These engine mounts collapse before they actually break.With the collapsed ones its hard to tell if they are stuffed or not,you would have to measure where an engine sits in the engine bay when its fitted with new engine mounts then and compare the measurements to the engine sits in the engine bay with the old mounts ..My engine sat about an inch or more higher in the engine bay after replacing them.They helped big time to get rid of a bad vibration. .My car had a bad vibration,I replaced the engine mounts,gearbox mount,the centre bearing and uni joints and all the rear axle control arm bushes.It runs perfectly smooth now.If the actual engine itself is vibrating,(my vibration was from the middle of the car near the transmission), then check the harmonic balancer.If the plugs ,leads and coils show to be ok then the air/fuel variation between cylinders error code could also be caused a bad oxygen sensor on one side, or a vacuum leak on one side of the inlet manifold.