Wipers/power locks/radio problems

Chevrolet Silverado 1500 pick-up truck, 1992, mileage 61,500.

I have 3 major problems with my truck:

1.- Whenever I need to use the winshield wipers, I never know beforehand if they will work; they seem to do it on a whim. I can hear the motor working, but most of the time they just dont' work. If it helps, I have noticed that, when they do work, the car and the day are cold. Do I need to replace something on the wipers motor?

2.- The power door locks don't work, at all. What is it I need to buy or fix?

3.- Whenever I turn on the radio, it turns off by itself (if and when it turns on.) I mean the radio is still on, but it becomes mute. I have to wait for about 10 days before it works again for about 2 minutes. Also, when it works, it sounds badly, like if there is also a problem with the antenna. What do I need to do? Thanks a lot in advance!