I agree, something is probably loose, I think on S10's, you can drop the bottom half of the steering column cover off (all the way on the bottom of the column under the dash, I know I could on my '91), that's where all the connections are for the wires that go into the steering column is. Wiggle that shit around with your wipers on and see if they start and stop when you wiggle the connectors and wires.
The wiper motor should be mounted right to the firewall under the hood, you could check for a loose connection there too, and checking to make sure the fuse is pushed all the way in is a good idea too. I know the '96 is a different body style than my '91 was, but I think all that kind of shit is basically the same. Hope that helps.