engine problem on 1999 Mitsubishi Galant

i have mitsubishi 1999 resently i repleiced the timming belt and valves but some times has a litle shaking and some time it is normal what can be te problem

1 answer
Did the shop replace the spark plugs when the timing belt was replaced, sometimes just a tune up will smooth the engine idle ( air filter, spark plugs,spark plug wires etc ) Start with a tune up and oil change before going any farther.