:confused: 92 honda accord shifts down to 3rd gear when going 70 mph, even if it's not going up hill, it just jumps out of 4th gear. I'm guessing is some trans. Sensor because sometimes when I try to start the car, the "D" flashes ( P,R,N,"D",3,2,1) and the car won't start. Any suggestions?

Automatic Transmission Gear Position Switch Replacement/Adjustment:

1. Remove console and disconnect 14-P connector from switch.
2. Remove both console switch mounting nuts.
3. Position switch slider to "Neutral."
4. Move shift lever to "Neutral," then slip switch into position.
5. Attach switch with both nuts.
6. Test switch in Park and Neutral positions of shift lever. Engine should start, when shift lever is in Neutral (anywhere in the range of free play).
7. Connect 14-P connector, clamp harness, and install console.

The above might be part of your problem. Ensure you have recently changed the ATF and filter. You may have a problem with the 4th gear lockup solenoid.