THis is quite symptomatic of crank position sensor failure, located on driver side of flywheel bell housing.
http://www.geocities.com/lmp4203/kia...nk_sensors.jpg....not as conspicuous as it looks in picture, though.
THis type of failure happens on almost all cars, (my sister in law just last month). THis component is heat sensitive with time and does just that: stops waiting at red light, or once you have completed market at grocery store....so this must be checked before all, (the 6 months it went well were the colder months of the year...)
but.... the Sporty is reknown to mimic symtoms that turn out false leads...so keep us informed of results.