Loss of power and engine rattle

I have had the dsame previosuly that lasted for around 2 months but cleared itself, however after a further 2 months the same problem has returned.
the problem is a loud rattle sound coming from the engine/exhaust, a vibrating gear knob, loss in power and a higher fuel consumption. I also have a hot smell coming from the engine. The 4 coil packs have been checked and are working ok.