I've found multiple topics using the search function on this issue, yet i am unable to find a solution to the problem in any of the threads (ie: https://honda-tech.com/forums/tech-misc-15/civic-issues-2821409/ ). So here it goes...

2000 civic lx. MT. Just bought the car yesterday. Noticed when i was driving it home that when i put it in neutral while car is in motion the rpm's stay at 1500-2000 rpm. When the car comes to a complete stop and only a complete stop do the rpm's return to normal. Ive cleaned the TB and checked for vacuum leaks and also shortened the idle screw in front of the TB cable. None of these have fixed the problem. driving me crazy so if anyone has been able to solve this problem, do share

 

Ok. I had the same issue. You should never mess with the set screw that the throttle stops against on the throttle body. You need to use a multimeter and check the throttle position sensor. It should read .5volts at fully closed throttle. Mine used to do the same thing and I replaced all kinds of crap before doing this one little thing. Check it and see if that is the problem. Good luck.

 

I've got this same problem.. so what exactly needs to be done to fix it if it isnt reading .5v?

 

If it is adjustable, you will have two screws holding the tps to the tb. Back probe the harness while it is plugged in and turn the car to the on position. NOT START.. Then you just loosen the two screws and move it one way or the other to get the desired .5 volts at fully closed throttle. Some tb's have more like a rivet holding them in and they are not adjustable.