Overheating issues

Still running just the cleaner and water, the car does seem to be doing a lot better. I'm using Thermocure cooling system rust remover. I think airflow might still be an issue however, as the temp climbs while idling in traffic. But cruising around at 45-90 the temp has stayed under 200. I think I will get the radiator filter, had no idea such a thing existed. I've tried removing the block drain plugs but they're stuck pretty good. Any more force I was going to strip them. I talked with my shop to have them try it, but it'll be a couple weeks before they can look at it.

I may be having another unrelated issue now. I think the IAC on the sniper efi is getting stuck. Sometimes at idle it hangs at 1200rpm (idle is set to 820). The other day I was trying to come to a stop and rpms hung at 2k, which makes stopping a bit harder, not too mention how much faster it launches when I take my foot off the brake. It's actually making the car dangerous to drive. The IAC was reading at 50% and only getting as low as 10, way too much. Later that day, it seemed fine. Either something needs reprogrammed or something is broken.