I have a 2001 Civic LX MT with no mods 187,000 miles. Had a stalling/ shutting off issue at stops. replaced the IACV (auto zone part). in 2 weeks no issues, now after driving it on the highway for 20/30 minutes at around 2,800 to 3,00 RPM (No overheating) when I did the head gasket new OEM thermostat, temp sensor, and all OEM parts on the job, the car will idle low once off the highway at a stop light, then dies. I get rpms at like 700 to 450 (engine oil light comes on) then shuts down, will start right back up and do this for a bit then ok. I have ZERO codes I have changed the IACV, did re-learn (4) times, and upstream o2 sensor (Denso) this only happens when it runs on the highway and not at all in stop-and-go. Any thoughts on this as-TIA