Idling at 5k,please help

[Nismo200R]

Okay the car overheated pretty bad one night. The hose clamp on the upper rad. hose came loose. I managed to get it home,and put water and coolant in it. Thenb it started to idle at 3k then i drove it for a while keeping rpms below 2k,and it idled at around there, then i got on the highway at about 80mph,and rpms were at about 4k. then when i got to neutral or push the clutch it goes up to 5. I blocked off the air regulator and it dropped. could this be my problem? also there is a really horrid smell coming from around where the air regulator is located. I cheked both the tps and the temp sensor. and when i block off the opening to the air box it doesn't affect it.

[SlowFiveOh]

a vaccum leak can cause a high idle but not that high. are you sure you did not mess with the throttle cable at all? move it, bump it? it may be binding causing the throttle to stay open