Hi,
I have a 98 Civic EX(LX in US) with automatic transmission
recently I found that it's engine keeps 300-500 RMP higher than normal on high way, e.g. the normal should be 2500 RPM at 100KM/H speed on hight way, but it keeps around 3000RPM

and it runs after around 10 KM then back to normal, if at the cold early morning, it get worse after 20KM back to normal RPM, I can feel that the torque converter is not lockup.
I changed ATF from dealer last year, Just checked the ATF, it's at proper level.
:thinking: