Fiesta petrol 1.25l power train warning light ?

Hi. Our car has had some starting problem for a little while as it isn't getting much use. We've had a new battery full service etc but still having problems starting. Occasionally it will just give a short grinding noise . After several attempts it may start. Yesterday it started over revving when it eventually started. During a short drive the revving started, wouldn't drive fast and the power train warning came on (Amber) . Turned it off and then started again and was ok for a short while. My partner is disabled and relies on the car so understandably I am getting concerned. Before I take it to main dealer can anyone please advise ? Thanks