My car has a slight but noticable vibration while one idling, in r or d, it has 150k miles, engine and tranny I've been told are good, motor mounts were checked and replace. Only code popping up was for o2 sensor and I took care of that(I know it has nothing to do with vibration). Oil change a few days ago. RPM was running low around 450 but tweaked to 700, helped a little. Had a mechanic say it's safe to drive.

Not sure if this helps, but I touched the engine myself, with e brake engaged, and with car in each individual gear, and it felt the same. I only notice it in the car.

I'm at a loss. I'm thinking maybe a vacume hose or the Idle air control valve. But wouldn't I feel it more while touching engine if that's what's causing it? Unless it need a tune up but I'm not getting any codes indicating I need one.

Please help.

 

From what you describe , it sounds like a good possibility there is a vacuum leak somewhere in the system. Finding it is like doing a little detective work and sometimes we find it right away and other times it can take some doing to pin down.Just replacing parts is not the best way to correct this, if that is the problem..
Diagnosing over the internet is not smart and can get expensive and disappointing.
I would suggest to have your vehicle checked out by a competent shop and go from there. It could be something simple and just take some time to find and pin down.

A side note,,, codes only provide direction as to where to start checking and rarely indicate a defective component. We still need to know where to look and what to check.
Tune ups are a thing of the past. Regular maintenance according to the owner's manual is the better thing to consider.