Rep Power: 0

97 Honda Civic Automatic.
155k miles
4Cl
On hot days over 90 degrees AND while driving the slow streets, the engine idles high after I have been driving it for a while. As it idles higher, the engine gets warmer and then starts to idle even higher (up to 3000 RPM) before I finally have to just shut the engine off and let it cool down.
Once it's cooled down a bit, I can start it back up and it idles just fine.
If I drive it on the highway on hot days, I don't have this issue. It's only on the slow streets AND on hot days. The cooler days don't cause any problems.

My mechanic has cleaned the IAC thoroughly, but that's about all we've tried.
The previous owner replaced the radiator himself, but I don't know enough about cars to verify his work.

Any suggestions are greatly appreciated.
-Michael

 
Rep Power: 222

Iac might need to be replaced, get an oem one

 
Rep Power: 0

Thank you!!