I've just acquired a 2000 LS400 and as I'm driving down the highway, I noticed a vibration that seems to have started immediately. I put it in neutral at 70mph, it goes away. Put it in park and rev, vibration builds slightly. It's not terribly noticeable but anybody familiar with these cars would notice immediately. Please help I am suspecting misfire? Also I have no clue when or if timing belt has been done. Odometer reads 150k however I noticed some 250k readings earlier this year on vehicle history report. Also no codes.