Here's the model:
1991 4Runner SR5 V6 Auto Trans 4wd
Has been a great truck since purchased new way back in 91..... trans has started to act up a little and need some direction.
TWO SYMPTOMS
1. When warmed up to operating temp sometimes trans won't shift out of 1st gear. Stop and restart motor and it will shift properly until it does it again.

2. Warmed up at highway speeds, trans downshifts fo no reason causing high rev of motor. Let off the gas and it will shift back into OD. Seems from the RPM that it is skipping 4th and dropping from OD into third.

Both of these issues are intermittent. neither seems related to the other when they occur.

About a year ago, Dealer replaced solenoids, not sure which ones. but need to plan for the repair and would like a little idea what I'm looking at before I jump in on a 30 yr old truck.

 

You probably have the A340H (look at the label on your door pillar). That's a "3-speed plus overdrive" transmission, so it's not "skipping" 4th. It does have a lock-up clutch; if it drops out of lock-up at highway speeds, it will rev up.

I'd start by looking for the receipt from the dealer. They probably changed all 3 transmission solenoids, but the receipt will give you vital background.

Next, I'd try checking for codes. http://web.archive.org/web/201408161...31diagnosi.pdf This will only tell you electrical problems, but that is probably what the dealer found.

I assume you've check ATF level. If not, go back to square one.

 

I am also about to do solenoids on my a340h. I saw some that were for the H and for the E. So is it safe to assume both transmissions share the solenoids?

 

Doing parts comparisons it looks like the E & H share the same solenoids. Have a look at the two kits near the bottom, it specifies that they are for either the E or the H:https://www.rockauto.com/en/catalog/...+solenoid,8476

 

Test your TPS first is free, if out of adjustment or bad your auto. trans. will start acting up kind of weird.


https://www.4crawler.com/4x4/CheapTr...PS/index.shtml

 

Manual shift tests are also free.

Symptom #1 makes me lean towards a ground fault.