i have a fiat punto reg 1.2 8V reg12001 ?

when I start the engine the yellow warning light comes on the dashboard I have taken it to my local garage to which they did a diagnostic check and suspected faulty ignition components so to date we have changed the ignition leads, both coils, spark plugs, and timing sensor, also when the engine is switched off and left for about half an hour and then switched back on the engine idles erratically, until I press the accelerator pedal to gain higher revs to which the engine settles down but the light still stays on.