1993 regal intermitant starting problems

My son's 93 regal has a problem starting after it has been driven and shut off. It will turn over but will not start until it cools off after a couple of hours. This only happens from time to time. It also runs rough sometimes when you give it gas , but when you let up on the throttle then give it more gas it runs ok. We replaced the ignition control module and the cam sensor three or four months ago when it wouldn't start weather it was hot or cold from time to time and it seemed ok. Now it seems to act up only when it is warm.