I have a 99 f-150 that the electric door locks have begun to fail. when you hit the button you can see the lock try to go up or down but it doesn't do it all yhe way. sometimes it will but most the time not. also the electric window motors seem to be slow. what should I check first . Thanks

 

I would pull the door panels and check/clean the connectors. Might have moisture in the door over time and corroded connections causing resistance.

 

Thanks, I'll try that. I'll let you know how it goes.