If idling (ie car stagnant but engine running) also can feel engine vibrate, & worst if aircond turn on...
then I will suspect engine mounting 1st, the top 2 mounting can visually check one, lower mounting need to let mech check, if u cant tell, just let mech look at it, if change all cost few hundred bucks, u can choose to replace d rubber only (take out old rubber, pump d new rubber into the existing bracket), use back d existing iron bracket, like this will be cheaper, but not all mech do that....(all taxi do that one..)
If car stagnant, engine running & RPM fluctuates.....then vibrate caused by d out-tuned engine......then do tuning & see how lor.....