High and low idiling after warm up

Hello. I am new to this forum, but it looks like there are a lot of good people here. Anyway, I just picked up a '93 pickup with a 22re. I am having a problem with the idle after it warms up. It drives fine, but when I stop at a light it starts to idle down like it is going to die and then it revs back up. I just changed the PCV valve and it didn't help. Any help would be appreciated.

Check for a fuel leak, and sometimes after you change a part in the fuel system it takes a little while to build pressure back up

Clean out your throttle body with some sensor safe throttle body cleaner. Start with the simple and cheap.