My car runs great, but I'm getting some vibrations around 1500 rpms give or take 250. I'ts not exremely bad, just enough to **** me off. and make the ride seem rougher when others are in the car. When the rpms are above 2000 or 1000 or less, the car runs smoothly. I find myself driving in regular drive, and not over drive just to eliminate the shaking. Any ideas?

 

My car makes the same vibration at 1400-1500rpms.
And I also drive around in D to avoid the vibration.

I noticed my back right spare tire trunk panel vibrated horribly at that rpm. Just last night I put in a new white plastic "nut", from Paddockparts.com, and it is very tight now, and does not vibrate anymore. See if that helps.

I've also read that with aged trans (100,000 up), keeping it in D at lower speeds is "healtheir". Technically, in D there is something that doesn't engage, so shifting doesn't put as much strain on the tran. Sorry for being untechnical, but its recall from memory, and I'm personally no trans expert. I read it in a trans/drivetrain forum post.