High and hanging idle - 5.3

[OneOffStroker]

I had to have my new-to-me 5.3 rebuilt because of bad cam bearings that resulted in little to no oil pressure.

Now that it's rebuilt, I started it up and I have great oil pressure now, but the idle does not go below 1000, and when I rev it a little bit, it hangs for 5-10 seconds before going back down to 1000. It did not act like this originally, and I'm not sure if there may be some kind of tuning/relearn issue, or did I just mess up something on my install.

It did not do this before the rebuild. The intake gaskets were replaced during my original install, but have been on/off a few times, but have only a few actual minutes of run-time on them. I have another new set of intake gaskets and throttle body gaskets from the rebuild that I may put on, but wanted to get some ideas first about if it could be tune related?