Blazer Grunts when going over Speed Bumps

I finally got my sloppy steering fixed but my Blazer still grunts when going over speed bumps (pitman, idler & steering box replacement).

When I go over the speed bump, my foot is off of the brake. I have replaced the shocks about 6 months ago. I have pushed on the front bumper and can not duplicate the noise.

The shop that did the steering box replacement suggested that it may be the bushings and that they would lubricate them……looks like they forgot. The bushings looks good (no cracking).

Any suggestions on lubricating the bushings? Is this a good idea? Can lubricant deteriorate the rubber bushings?