I have a 1987 automatic EFI 4x4 Toyota 4unner.

Most of the time when I take off at a stop light, it works perfectly.

But sometimes when I take off, it accelerates very slowly and the over drive light next to the radio flashes on and off. When I get to about 30 - 40 MPH, it starts accelerating correctly again.

What's wrong with my truck?

 

search on this issue, there is lots of info on it.
It's caused by the shift solenoid. when the computer detects an issue it defaults into a (limp home) mode. thats were it defalts into 3rd gear. if you shift the trans manualey it should shift fine. I've been having the same issues with mine. I pulled the pan and cleaned everything out, tested and cleaned the solenoids, reinstalled with fresh oil and filter. works fine now.