racedvl,
I've had the same problem. Seems like the locking mechanism and the button have a large clearance/space tolerance. I've had the passenger side not unlock when locked manualy or by the key. The problem went away when I switched the door lock switch. My guess I must have moved thing inside the door panel. Best way to get rid yourself of the problem is to lock/unlock the truck with the power lock button.
Even better, like I just did, install a security system that uses the button locks with a "clicker". You can even just install a remote lock/unlock system for less than $70.00. My truck will now lock the doors when I turn it on and unlock when I turn it off. I can by pass this feature by having the door open then turning the key on. Security and no more door key!!!
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gchemist
1983 Custom Truck
TX Plates: "BAD BOW"
http://www.geocities.com/abetterchemist/