door locks

[quote:f8ded79d1c="leecoga"]1999 Chevrolet Tahoe 4D 4WD 350 automatic 120K miles:
Both front door locks are working intermittently when triggered both by keyless remote and door switch. When lock/ unlock buttons are mashed repeatedly door lock mechanism becomes weaker and less responsive to the point of not moving at all. Rear doors work fine. Both door lock actuators and door lock relay switch have been replaced. Any advice would be appreciated.[/quote:f8ded79d1c]

Are you sure you replaced the main door lock module? It really sounds like an intermitent main control module for the lock system. I think they are all located above the park brake lever up to 1999. Flat black box and I have installed replacements that were bad right out of the box. Probably a unit that had been installed by someone else, ruined, and returned. It's a possibility.