I have a 91 accord, auto trans. The car did this about a week ago. I fixed it by resetting the idle and it worked for a few days until it decided to do it again. I'm gonna see if resetting the idle fixed it again, but it seems that is only a temporary fix. Basically, the car takes forever to accelerate. If I shift it into first manually it takes off fine. Also when I'm driving anywhere past 1'st gear, it likes to decelerate on it's own while I'm coasting. As if it downshifted on it's own or something.

anyone know what causes this?

 

A lot of auto transmission related problems for the 4th generation Accords (90-93) are due to the Transmission Control Unit (TCU).

If transmission fluid level is okay, then you may want to read this link:

Honda Electronic Transmission Problem- Troubleshoot, Inspection, Repair, Replace.

 

That's an excellent link that helped me diagnose my own car's transmission issues. I still had issues even after swapping in another TCU. Mine ended up being a simple removal, clean and replacement of the shift solenoids...also highlighted in that link.