2008 Tahoe LT 4x4 90k miles. New brakes/rotors fr & rr. When slowing down from about 30 mph I hear and feel a subtle shudder or vibration, not strong, most passengers can't feel it. Interestingly when I put it in neutral the "sensation" goes away......something in the drivetrain?? While trying to figure out what's causing this I discovered the drivers side engine mount was busted in half so I replaced it and figured I'd found/fixed the problem. Well it is definitely better but the shudder is still there. Got under the car this morning with a pry bar to "test" the tranny mount but couldn't get enough leverage even after jacking up the front end but it feels solid. A close inspection with lights and mirrors shows the mount to be clean with no cracks. Anyone have any ideas?? thanks