Stumbling Idle
 

So as soon as it got warm out, my idle started to act up. It's not ridiculously harsh, and it only made me stall once, but it's not normal. I just changed the coolant temp sensor with a genuine Subaru one. It definitely helped, but it's still there. Seafoamed it through the intake hose right under the plastic cover (the smaller one on the passenger side), and that also helped, but it's not cured. It kind of bounces around (much more gently) 500rpm, then settles out, then starts bouncing again. If I turn on the AC, it goes away completely, not even a hiccup. The TPS is at exactly .50 volts, but I'm not entirely sure it's good. I'm going to take it out tomorrow and test the ohms to make sure it's good. I'm also going to check the air filter and clean out the MAF and see if that helps. None of the vacuum hoses seem to be cracked or missing or anything. My O2 sensors were replaced not too long ago (those caused a very harsh idle). No CEL. Anything else I should check out? It's more of a nuisance than a worry because of how mild it is.