Yesterday my mom's Honda accord 5th generation developed an automatic transmission issue when hot. If I start from standstill, it feels like is engaging 3rd or 4rd gear (as it feels different from 1st or 2nd).

If I manually shift at intended speeds and no WOT from 1st to 2nd to D3 and D4, the shifts are ok (no slippage or anything), but as soon as I press the gas harder, if in D3 or D4, the tranny tries to shift down, but fails to keep the new gear engaged, and shifts back and forth between gears really really quick.

After stopping, the D4 light starts blinking. So I pulled the code with a wire, and got 9 blinks. According to my manual, that's for countershaft speed sensor.

But here is the funny part. I realized that the speed gauge is jumping up and down in a funny way, but the ECU doesn't give any code for speed sensor.

This is the 3rd speed sensor of the car, but usually the other 2 died instantly. I tried disconnecting the vehicle speed sensor, and the jerkiness in shifting goes away, but the car wont shift by itself (it starts from 3rd or 4th). My mom doesn't recall this "unable to shift by itself" being a symptom when the other two VSS failed.

Plus the computer gives code 9, and only gives codes in the D4 light.

Any ideas?