2002 Fiat Punto Shaking engine and low power

Sounds like a misfire. Have the PCM scanned and it should have a code stored for the cylinder that is missing. If not, when it is idling, use a water bottle or crayon and spray/mark the exhaust manifold at each cylinder, the one missing wont evaporate the water or melt the crayon as fast or possibly not at all. At 77k you may be due for a tune up, but if it misses all of the time it could be abad coil or injector, but start with the basic tune up first