Your car has a three cylinder engine. If you are facing vibration while standing still, my guess is that one of the three cylinders is not firing or not firing properly. I am not familiar with the layout details of the Mira engine. My guess is that your engine has the coils built into the plug wires. It is possible that one of the coils is weak or the spark may be grounding out.
If the coils check out, then the next culprit could be a faulty valve. Faulty valve can be found out by a compression test. If one of the valves is faulty, it does not fully seal when closed. Because it dose not close, compression value of that cylinder will be low.
Usually if one of the cylinders is not firing or not developing full power, it is characterized by both poor acceleration and fuel economy.