2000 Durango idle/shifting concern

I recently purchased a 2000 Durango with 151K on the clock. It looks like it was well taken care of, clean inside and out, and runs/drives nice. I just have 2 "concerns". There are times when the vehicles shifts from 1-2 and 2-3 it "shudders", only does it for a split second, and seems mainly when pulling out on some sort of upgrade, but not always. Otherwise it runs and shifts fine.

The second "concern" is that it seems to surge a little at idle. At a warm idle in park is when I noticed it. It goes from about 750 rpm to 950 rpm over and over. I havent really noticed if it does it during regular driving.

I really like driving it but dont need to rely on it for everyday use. I've read the posts on this forum about these problems, but it doesnt seem like my issues are nearly as bad as most posted about them. I really dont want to just start throwing parts at it and hope for a solution. Any ideas? Thanks.

I noticed over the weekend that as the vehicle warms up, the idle will go up as well. It idles at around 800 rpm when I pull up to a stop light (in gear) but doesnt vary from that. Only when I put it in park does the idle wander. This morning it was going from about 750 to about 1100 rpm in park.