I just got back from a road trip and when I stopped at a stop light headed home the rmps in my car were up but I was stopped. This has continued to happen all week, my rpms go up when I am in neutral or am stopped and then they go down a little and then down a little more. The check engine light has not come on and the rpms are up around 1,5 to 2 so it is not that high but I am still concerned.

I took my car to have it looked at and they said it might be the alternator but they really couldn’t be sure…Any thoughts?

When RPMs vary up and down considerably, the first thing that I look for is a vacuum leak.

What kind of transmission??

2000 rpm at idle is definitly the sign of a problem,you should be concerned.

I’d consider the Idle Air Control circuit also a good candidate.

Here, I found this link that’ll give you a good insight into it.