Why do my front door speakers not always work in my car?

I have had my stereo system in my car for quiet a while. The door speakers are stock, the head unit is not, and I added 2 10 inch subs with a 1000 watt sony explode amp. The whole setup has worked. Recently though my front door speakers stopped working. They are off most of the time but sometimes they'll randomly come on (going around turns, stopping, sometimes just cruising) and they'll stay on at that point until I shut the car off (most of the time). It leads me to believe that its wiring but I've checked all of them as far as the head unit goes. I even put the stock unit in and it didn't do anything.