Picked up my first 4runner this weekend. 1992. 3.0, 4 speed auto, 4x4. First vehicle like like since my jeep 10 years ago, thus my username.

It runs great. 1st through 3rd shift smooth. However, when I'm on the interstate I really cant go above 60 without pushing the RPMs too high. I've counted only 2 shifts from starting from a stop (1-2 and 2-3). It's great for in town driving, but not so great on the highway currently.

I'm sure its on the original tranny fluid. Dont want to change that. I'm sure it could benefit from a filter change. But before I start troubleshooting blindly, any advice? I checked the O/D button on the shifter. On or off had no impact. I've seen things about solenoids, sensors, etc.

I guess my questions is what should I address first? I thought I was onto something earlier when I realized a valve was removed from my truck, but it turned out to be the heater control valve.

 

The transmission you have (A340H, A340E, ....) is on the sticker on the driver's door pillar.

Both lock-up and overdrive are inhibited when the engine is cold. http://web.archive.org/web/201408161...20electron.pdf
You might want to check the ECT sensor. http://web.archive.org/web/201411140...98engineco.pdf
You might want to test-drive with the solenoid connector disconnected, as described in the above link, to see if the transmission will engage O/D at all.