Wiper problems

[GMC1987]

I have a 1987 Gmc truck with delay wipers and the problem that I am having is that when I start the truck, the wipers cycle once and then while driving the wipers will cycle every now and then, I have replaced the control arm and it still cycles, so when it is not raining I have to pull out the fuse to stop it. Is there anything that I can do to stop this problem, also my two brothers have Chevy trucks and they have the same problem with their wipers. Any ideas.