With my 93 Auto at 255k the transmission has been going for about a year - once it gets warm 4th and reverse slip, I know they're the first to go.. but since I've installed a Hayden 403 cooler for it, 4th is better, reverse the same, and now it wants to wait till very high rpms to shift, like 2nd-3rd at 45, 4th at 70, I mean that's cool but come on Honda. Is this just the transmission continuing to die? Is it too cold? The fluid is at the right level but pretty black, would flushing help?

 

Draining/Refilling/Running for 15-20 minutes, and then repeating w/ Honda ATF could provide a boost to your trans performance, but no garuntees. A used trans is your most cost effective repair. Check car-part.com for a replacement part near your zip.

Any work on throttle body or trans that could have disturbed the throttle cable link to the transmission can affect shift quality.

Also check for trans codes even if D4 light is not flashing. Several electrical trans codes don't set the D4 light flashing. If you have one of these, the fix could be simple and cheap.

good luck