Two ideas,could be where the lock cyl. hooks into the latch or could be the shaft of the lock cyl. is woreout.My drivers door did the same thing,shaft was half wore through,if you change cyl.you may have to do some triming on the cyl.as the locks I've seen are made for metal doors not fiberglass and it takes some tinkering the get the clips in place,you'll see what I mean when you compare the locks.
Next,the power locks,if either switch is disconnected then neither side will function,also there is a ground wire for the system on the pass. door that could be the trouble.
found some problems, pulled off both door panels and both electrical wiring harness wirire are about wore through, also looking at the drivers lock rod, it looks like it needs to be adjusted. maybe when i order the new power door lock wiring harness i will order 2 new rods,along with clips.
Still better check the lock tumblers,they hook directly to to latch assembly,the lock rod has nothing to do with the key side of the lock. Depending what you need you should be able to buy pigtails with the plug for about 15 bucks.
Coming oout of the back of the tumbler is a shaft,connected to that shaft is a stamped steel piece (tab) that hooks to pin that is the locking mech.of the latch asm.Now if someone had the latch out they may not have lined tab with the pin.Or the tab might have cut a slot into the shaft letting the tab turn without moving the lockpin.Try taking out the 3 screws that hold in the latch (there the 3 in the rear of the door),drop the latch down and hold the tab while turning the key,you should have very little side to side movement in the tab.Hope that helps,if you still have problems email me with your phone and I'll talk you through it.I know my directions may be a bit vague.
check tumblers and they are okay, so i am just waiting for rods/clips and power door lock harnesses to do the doors. went to the doctor yesterday because i have been having bad pains in neck/shoulder/back and was told it was pulled muscles/nerves , doctor told me not to lift or do any type of bending for a week, so my son has volunterred to do the repairs on the doors when the parts come in, of course i will be there to supervise.