I have a 91 Toyota Previa with only 356,288 miles plus what my wife drove today. It has a four speed automatic- factory installed. Reverse engages correctly on a cold start but is slow (a few seconds) to engage when immediately stopped when hot. If it sits about 15 minutes after shut down when hot it usually will not engage reverse but if it sits for about 45 minutes it usually engages in a few seconds or less. Have you (whoever is reading this) had a similar problem and if so gotten it resolved without pulling the tranny?
The chances that anyone posting here on the CarTalk Forum still owns a 28 year old Previa is beyond miniscule. That ANYone still owns a 91 Previa is beyond miniscule.
I think it is very unlikely this transmission issue can be addressed without the trans coming out… and being completely rebuilt. But I could be wrong.
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Have you checked the fluid level ?
I’m with @Mustangman on this one
It sounds like the automatic transmission has mechanical issues . . .
This vehicle owes you nothing. You’ve hopefully gotten your money’s worth out of it, and I’d say it’s time to move on to something newer and with a lot less miles
Is the atf level correct?
Are you using the correct fluid?
How often have you been servicing the fluid and filter?
What condition is the fluid in right now?
Bright red?
Black and burnt?
Even though I don’t think this well help, I’ll throw something out there . . .
Have you tried high mileage atf . . . the kind that supposedly helps in regards to worn out seals and clutch packs?
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See below 
This transmission probably has a Simpson gear train followed by an overdrive. One problem area of the Simpson gear train is the direct/reverse clutch. When the direct/reverse piston seals get old and cracked, the fluid pressure leaks and the clutch will slip when the oil is hot. At cooler temperatures the oil is viscous enough to allow the clutch to be locked.
This means that you will need to have the transmission rebuilt or a used low mileage transmission installed. I looked online and a used transmission runs for about $660. In any case you are probably looking at a price that exceeds the Blue Book value of the car. You have gotten fantastic life out of this car so it may be time to get a used, younger, lower mileage vehicle.
I agree with the previous replies that your transmission sounds like it’s on it’s last legs, with hardened-aged seals being the likely problem.
Since you have nothing to lose, you may want to try a can of Berryman’s Chemtool. A transmission expert who used to frequent this site (transman618) used it often in aged transmissions to soften up hardened-aged seals. It’s not a product built for transmission use, but it’s reputed to help.
Here’s one thread where he discusses it.
There are more. Just search this site for old threads about Berryman’s Chemtool and/or threads from transman618. Consider it a bandaid, especially where you have nothing to lose.
See below. I learned the system only handles text from the last reply - and I interspersed my reply with the original so here goes below.
It sounds like the automatic transmission has mechanical issues . . .
– some kind of issue anyway
This vehicle owes you nothing. You’ve hopefully gotten your money’s worth out of it, and I’d say it’s time to move on to something newer and with a lot less miles
– I love it , my wife loves it - getting it to pay me more is not the issue.
Is the atf level correct?
– Yes
Are you using the correct fluid?
– yes
How often have you been servicing the fluid and filter?
– drain and add fluid, about three quarts, about every 2-3 oil changes
– umm filter??
What condition is the fluid in right now?
Bright red?
– yep
Black and burnt?
– nope
Even though I don’t think this well help, I’ll throw something out there
Have you tried high mileage atf . . . the kind that supposedly helps in regards to worn out seals and clutch packs?
– not yet, I figure that if I put that in and it does not work it is an entire overhaul and extra bucks to clean the tranny. But might do it anyway if can not solve it any other way.
– Thanks for the suggestions. Again!!
Chuck
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