engine problem

increased emissions, service engine soon, and serious performance loss. also
has very hard vibration and harsh idle. still vibrates when clutch is depressed.
one mechanic told me it is the rod bearing(s). it has multiple misfires. the
vibration problem and power loss came before too but a simple spark plug
change prevented it for a month. After swapping all the plugs and oil change
the problem doesnt go away. it started with a metallic ticking noise and
developed into more. It now sounds much worse almost like the cylinder is
swooshing around