To answer your question yes I have resolved many poor idle quality complaints in a 103 motor. The resolutions are varied and somewhat expensive. First question is how many miles are on the engine and fuel injection. Another consideration is the engine suspension/ motor mounts. If they are weak there will be vibration transfered into the chassis. The transmission mount is equally suspect. That being said the possibilities, that engine is prone to carbon deposits on the intake valves causing all sorts of trouble as they disrupt mixture flow as well as valve closure. They can be inspected with removal of the injectors and cups and insertion of a bend a light to visualize the valve stem. here should virtually no carbon at the valve tulip. Next are the injectors, they are constant flow injectors, not timed or sequential injectors so after time the quality of atomization deteriorates. They need to be tested when removed. The fuel distributor is really suspect, it delivers fuel to individual cylinders through slits cut with a laser, very very small so wear and change in diaphram function cause all types of problems most notably idle quality. The possibility of distributor cap and rotor as well as ignition resistors at the plug wire end are also deserving of attention. Start with Techron treatment for three tanks and see what changes.
Bill