Clutch changing - 1997 Mitsubishi Eclipse

This sounds like the clutch, at the engine end, has a problem. The clutch plate might not be releasing correctly. When the engine is Off the clutch isn't spinning so doesn't affect the gear change. You might need to have the clutch replaced.
Your only sensible option is to get a Good Mechanic to remove the gearbox and inspect the clutch parts.
This, unfortunately, will not be a cheap fix.

not a clutch problem unless you have just done a clutch kit change
more likely a hydraulic clutch problem ( air in the system) or master cylinder needing replacement .
if it is a cable operated clutch , replace the clutch

From the way you've described it your gear stick linkages maybe on there way out. When changing gear does the car resist getting into gear?

If it's more of a crunching sound then I would try double de clutching, to do this you need to:
change gear as usual but instead of holding down the clutch throughout the gear change hold it down to take the vehicle into neutral then release the clutch then push the clutch down again and change into desired gear.
To change down it's basically the same principal but you push down the clutch to put the vehicle into neutral then push the throttle down just to pitch revs then release the throttle and push the clutch down to change into your desired gear, if it won't go in to gear easily then rather the throttle until it does.

You can go onto youtube and search for double de clutching and I'm sure some results will come up

hope this helps!

From you description I would suggest a change of the master cylinder

Where is clutch engaging? close to firewall or up high on pedal. If up high, your clutch needs replacing, Low, your clutch is ok, maybe throwout bearing is bad or air in system or not adjusted correctly

The clutch should go to the floor =) But if it's not disengaging the clutch disk, there's definitely a problem between the pedal and the clutch disk. I'm guessing you have a hydraulic clutch?

Clutch slipping is clutch itself. Caused by wear of disk and springs. Remove transmission and replace clutch...:-(

right the steeper motor is playing up which is why the engine is taking a long time to drop RPM as for teh clutch its auto adjust so if clutch worn then renew it ,clutch life depends on the driver so i can get 150.000kms out of a clutch and one of my customers only gets less than 20,000kms out of a clutch as he pulls away in second and slips clutch when changing gears ,i cringe when i hear him driving past the yard

hi it seems your clutch is losing pressure,it works like a shock, known as a hydrolic clutch, i recommend you change it asap.

you have 20k miles after the clutch has been changed, now are you used to drving clutch, secondly is it hydraulic or cable controled clutc?

if you are used to drving clutch sys probable cause is defective pressure plate or the throwout bearing is not fully releasing in other words the clutch is partialy applied all the time because of the re;ease bearing not fully releasing!!