1998 Other Hyundai Models Car wont start when running hot,

Engine Mechanical problem
1998 Other Hyundai Models 4 cyl Front Wheel Drive Automatic

After a short drive the car will not start straight away, it takes up to 30 mins to cool down and then starts
this problem started after a long ride down a dirt road
im thinking self timing switch? or maybe the coil pack?
My car is a 98 Hyundai Exel