Last summer, the 4wd actuator started making a grinding noise down the highway. Whenever i pressed the throttle, it would make noise. I replaced the one-way vacuum valve, and the solenoid. The issue continued, but now more sporadically, not just on throttle application. Whenever I hit a bump, the grinding would start. Sometimes it would go away, other times it would continue until I activated 4wd. I replaced both actuators at the wheels, as well as the vacuum lines leading to the actuators, and still the problem persists.

Has anyone else had this issue?

Thank You

 

More than likely the IWEs are damaged and need to be replaced.

Search for IWE and you'll find many threads.

 

Have you tried pulling a vacuum? Sure sounds like you still have a leak.
Who replaced the IWE's? Was the spindle nut properly torqued down? Were the splines meshed or vacuum pulled when torquing down to 30lbs?

 

my driver side went at 30,000 km
and pass side about 10k later

there is technical service bulletin on this issue

 

The first mistake you made was ignoring it till it became worse. Diagnose the problem, then fix the problem and stop trying everything that might be the problem but was not.

A good start if asking for advice is describing your year/model/ vehicle and engine.