88 F150 won't run when hot

my girlfriend has a very ummm rustic ford truck that runs great until it gets warm, then, not so much. its fine until it gets a little hot then it dies and will not start until it cools off. it turns over, lights work, horn honks, but just wont fire. she changed the coil and cilinoid. what now? 351 v8

Test for spark when it’s hot. If there is no spark replace the ignition module mounted on the distributor.



or thats closer anyway

It’s more than likely the ignition module mentioned by Tester. This truck is a TFI model and module failures due to heat are very common.