Electric lock puzzle in Suburban

The puzzle: 1999 Suburban LT w/ electric locks that are having fits.
The symptoms: There are times that ALL of the locks cycle just fine. There are times that
the driver's door and the driver's side rear passenger door just do not work at all then will work again. If you continue to cycle the locks, the front passenger and rear passenger door locks only operate half way. Stop and wait a few seconds and they will cycle just fine.
The REALLY strange thing, leave the dome light button set so they come on when you open the doors and they may not turn off after the 10 second delay when the doors are closed AND they may turn on very briefly when coming to a stop or flash when hitting a bump while driving. Turn the button off and they never flash, but of course they do not come on when the doors open either.
What I've tried to this point: I thought maybe there was a loose connection in the driver's door so I pulled the panel, checked all connections and the cycling of the solenoid for that door. Everything looked good and operated as it should. No binding, smooth operation when it worked, etc. Next I located the relay for the door locks that is mounted to the left of the center heater duct under the dash. This is the six terminal relay. Pulled it and the dome lights operated as they should after the doors are closed by going off after about a 10 second delay. I thought, OK it's gotta be that relay causing the grief. Replaced it since it doesn't cost much and the SAME things continued to happen!!!
Questions: 1. I could hear another relay (?) clicking somewhere even with the black six terminal relay removed when pressing the lock button in the lock position. Is there another relay somewhere under the dash?
2. If one of the lock solenoids is weak, will it affect the others this way? All cycle smooth and then start only half cycling or not at all?
3. Suggestions of where to look???
Thanks!
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Replace the door lock motors that are quitting and for the dome light check where the door panel is supposed to touch the dome lamp switch on the side of the dash you will most likely find that the distance from the button in the panel to the switch has increased over the years GM makes color matched shims to go behind the buttons to repair this, if this condition is present
Good Luck.
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