Aceleration problem

I have a 1995 Ford escort with over 175,000.00 miles. We have replaced the timing belt, cam sensor, and we are still having problems with our car. When you step on the gas it is like something is missing it hesitates. When you are driving and take off from a light or want to speed up it hesitates like it is going to stall. When we are driving on the freeway at a speed of 65-70 miles sometimes it starts to hesitate and want to die. I have been going to a repair shop for 6months + for this problem everytime they fix it they say problem solved it running great but then we drive off and we still have the same problem.