Try this:
Create your RAM preview. As you said it the time line cursor will return to where it was when you started.
Then set your time line cursor to the beginning of the area you just previewed and hit the space bar the section will start playing, hit the space bar again to stop it where you want and it should stay put.
You don’t need to do the RAM preview for this to work but if you don’t the preview will chug slowly depending on the complexity of your comp.
Kevin