Don't know if this will help but, my ty wipers sweep once before the truck starts. It started doing this after I cracked the wiper motor cover. So you might want to check that out.
It's a fairly common problem with these trucks (mine does it to). Basically, the switch gets dirty and/or wears out and you get random wiper action. Let me see if I can find a thread or two that will help.
________ SaraFox live