RPM and Clutch Problems

[Splendid]

Hello all,

I have an 1989 Honda Accord LX-i
~8,000-10,000 miles on this clutch

Now I know enough about the workings of a car to preform more than average repairs however I have never worked on a transmission or clutch before, I have been on doing some research and am willing to learn more.

When I'm driving along and press the clutch in, if i'm ABOVE 2500 RPM the car will idle at 2500 RPM. Discordantly if i'm BELOW 2500 RPM when I press the clutch in the car will rev until it reaches that point then remain.
It has only recently (as of 2 days ago) started doing this. I can't see this hurting the car, but it ruins gas mileage, which is also lower than it should be.

If I have left any useful info out please let me know and I can get it.
Thanks in advance

[Oldblueaccord]

Coolant needs to be full the IACV uses it to judge where the idle should be.

The throttle cable needs some slack at idle. IT IS NOT where you adjust he idle.

Throttle body plate needs to be clean and the shaft not worn or it wont rest correctly at idle.

Look for possible vacuum leak and check the ECU under the seat for a code.

[MessyHonda]

does the car idle normal at all or is it all the time that it jumps up to 2500?