power locks all doors not functioning

My 2000 windstar power locks recently started acting up. Pressing the driver's side lock/unlock switch will sometimes lock and unlock the driver's side door but usually only on the first try and only if the car has been sitting for awhile. None of the other locks work.

If I press the switch again, it won't lock. I can hear the clicking noises and the locks on both doors move a little but won't lock/unlock the entire way.

Due to the fact that it works on the dirvers side door (only) the first time but not on repeated pressing (and gets weaker and weaker with each press) seems almost to me like a power issue. I've read the post on the actuators but I'd be surprised if they all went at once.

Any hints on what to troubleshoot first?

My 2000 windstar had the same problem, I fix both front doors for about 20 bucks after reading a post on this forum. Here is the link:
http://www.automotiveforums.com/vbulletin/showthread.php?t=439893

Yes. I've seen that post, thanks. But do you think it could be the actuators based on the fact that all of them have seemed to go at the same time (the rear doors as well as the back lift gate too)?

I am not sure about this one but you might want to start out with fuses and relays. Im thinking more around the relay area. Sorry.. Not real sure on this one because all are acting up.. But still look at relays first.