Windshield wiper intermittent function not working

[kjlj]

My 2000 impala windshield wiper intermittent function is only working some of the time. Some times the windshield wipers run continuoulsy without any delay and some times they run correctly with the proper delay. Some times the wind shield wipers just stop in mid stroke up high on the windshield. Is there a timing module that could be bad?

Thanks.

Keith