2001 Front end chatter noise

My 2001 Tacoma 4X4 5 speed manual pickup makes a chattering noise that is intermittent. At or above 20 mph it will start with a chattering noise that will continue to cruise speeds then it quits. If I hit a bump, it will start up again and if I hit another bump, it will quit for a while. I have replaced the front brake pads and calipers recently and that did not solve the problem. My mechanic is also stumped. He says to drive it till something breaks. I don't like that idea because I work on large ranches and don't want to be broke down in the middle of a ranch with no cell phone service. Mechanic visually inspected CV joints but they are sealed so nothing could be done. The noise is more pronounced on the drivers side. It is so annoying because sometimes it happens in town and people look to see what the noise is. I really like this truck and keep the scheduled maintenance up on it but this is really bugging me.

I was wondering if anyone else has had this problem. I did a search but could not find anything specific to a non-modified truck. Any ideas what it might be would be appreciated.

 

Check to see that the sway bar end link is tight on both the control arm and the bar itself.

 

Driveshaft center bearing, perhaps.

 

I had (and occasionally still do have, until I regrease) some really bad noises coming from the front U-joint (right after transmission) of my driveshaft. The sound seems like it comes from the front end, when it's actually coming from almost underneath me. It took a lot of poking around and trial-and-error for me to figure out what was going on, but there would sometimes be squeaking, sometimes a "chattering", and sometimes a grinding/grumbling, with similar "bump-on, bump-off" circumstances to what you're experiencing.