I have a Honda Civic 2005 VTi Oriel Automatic, and there's an issue with gear shifting. When the car starts and it's cold, let's say I keep it on for 5-8 minutes, so when I drive it, the gear shifts late. For example, the 1st gear gets changed after 3000 or 3500 rpm. However, if I drive it for some time, turn off the ignition, and start again, then it works fine; the gear shifting works smoothly.
Also, if I drive the car regularly for 3-4 days, then in the morning, I don't face this issue.
Another thing is, on the highway, when I reach around 140 speed, then it starts missing, like it's not shifting gear. What could be the issue? Is it related to the gearbox?
P.S. The gear oil has been changed