Running Rough on 1999 Hyundai Tiburon

Hello, My daughter recently purchased her 5speed, 99' Tiby with 58,000 miles and its in fine shape. After her first week of driving it she went to the pump and filled up with regular unleaded. Right now the car is barely running. Could this be a coinsidance and there is another problem or do these 16 valve engines get cranky without higher octane unleaded. Thanks you so much. PS, If it is a fuel issues, is it best to run it through or should I turn the car over and empty the tank? LOL

Asked by for the 1999 Hyundai Tiburon
uh anyone still looking at this they only run on 91 and up replace the plugs and fuel filter and it will run right
1 more answer , 1 more comment
Every car made to be driven in the USA has to run just fine on 87 regular. It is required by the EPA. Is there a Check Engine Light On? Best to have a good diagnostic tech inspect your car. Are you sure that the gas from the gas station was not dirty. It does happen. Good Luck!
Yep u ride the short buss!!!!!!!!