1998 Hyundai Elantra timing?

My cousin came to me with her 98 Elantra, the car has 149,000 on it, and its throwing some check engine codes. One is the timing control sensor. Would this be causing the car to stall at stop signs and stop lights? If so wheres it located and how much would it be to fix it? If we didn't change it could she drive about 1800 miles (shes going to visit a friend) or is this a problem I should address right away? Thanks