Vibrate under deceleration

[G_Raw]

I know there are a couple threads similar going. But symptoms are all different.

Here's the background: 99 4runner 2wd recently lifted with OME lift and 285s.

Shortly after I noticed that when releasing the brake pedal it makes a pop type sound that feels in the pedal as if a shaft is sticking somewhere.

Shortly after I noticed while freeway driving I released the gas pedal and felt and heard a vibration in the floor. I felt it a second time. Turned the radio off and couldn't replicate the noise.

Thoughts? What do I go checking first?

 

[catrains]

since it is very old do the brake fluid change ..
master cylinders do cause problems when the old fluid causes a seal issue on the master rod.. try it .. change all the brake fluid..

 

[turbo8]

Check your lower control arm bushings.

 

[jgue467]

driveline shudder? carrier bearing needs a drop to compensate?

 

[G_Raw]

Master cylinder is less than a year old. Brake fluid is 4 months old. I did it when I changed the master cylinder and then when I did my TBU 4 months ago.

what's the best way to check LCA bushings?

Jack it up with wheels off and wiggle? Or actuall pull them?

Update: got under it drive shaft has what I suspect is normal wiggle ( 1/4" in either direction maybe?, flange on 3rd moves with it). Got no play when focusing my strength on the u joints. The rubber seal between the inner and out shaft doesn't look that bad.

I also can't illicit play in the lower arms. Bolts are pretty damn tight so I don't suspect they are loose. Do I mark the lower arms ( so i dont mess up the alignment on reinstall) and such and actually pull them to inspect bushings?

Possible hissing near power steering pump? But I recently changed the reservoir and o ring which stopped my PS fluid leak. Vacuum leak near there? I couldn't find one. Could the hissing sound be coming from the valve cover gasket I've been postponing ?

I couldn't replicate the vibration today...

Starting to become convinced the sticky feeling in my brakes is the brake booster rod...which means a vacuum leak could still be present if that's going bad.

Was going to swap third member as a means of regeari mg and adding a locker...high angle pinion to correct things? Or is that completely unjustifiable

IDK... thoughts?