Car: 96 Civic with b16a2 swap. ECU is 37820-p2t-a11
Whenever I'm cruising in gear then put the car in neutral, the rpm would stay at ~1500RPM the whole time only until like 2 seconds after the car has come to a complete stop. When the car is at a complete stop, it would idle fine at ~750RPM. I can't seem to figure out why it is doing that

List of things I've done:
-Clean IACV then bleed coolant. Also cleaned TB
-New spark plugs, spark plugs wire, dizzy rotor & cap, pcv valve, fuel filter.
-Measure TPS voltage reading. .51V at closed throttle. 4.61V at WOT
-Made sure TB closes all the way. There's a good enough of slack on the TB cable and i can hear the metal to metal sound when the TB closes.
-Reset ECU through unhooking negative cable from battery then did idle relearn.

Currently no CEL but the most recent CEL i had in the past was P0505. I fixed that after finding a vacuum leak. Car currently drives perfectly fine.

Not sure what could be causing this. Is .51 volts too high when the throttle body is closed? Should i calibrate the TPS to .45V instead?

 

calibrate it to .48 at closed but do wot to 4.5 first
https://honda-tech.com/forums/tech-misc-15/diy-how-calibrating-voltage-your-tps-sensor-2947986/

my car does this same thing and I have never figured out why so subscribed

 

I did the idle relearn and adjusted my idle a bit again last night following the instructions in the manual and now it's idling constantly at ~750 RPM even when I'm rolling in neutral. Weird how I did this before and it still idle weird. Not sure if the issue will come back but I'll report back.

 

I've always been told its normal to idle a little high when the cars rolling. In neutral or just having your foot on the clutch should act the same.