Highway Downshifting Gears. on 1992 Toyota Paseo

I drive a few city streets and then jump onto the highway when going to work every morning. When I finally hit the highway, it will switch from the highest gear to the next lowest gear, making my engine rev higher than it should. After driving a few miles, it will then resort back to the highest and most efficient gear. I'm wondering why it is normal at first, then jumpsdown a gear, clearly after the engine is already warmed up, and after it has used the highest gear on the highway a few minutes before.

by in Overland Park, KS on May 03, 2011
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1 answer 2 comments
ANSWER by , May 03, 2011
engine load. if you are on a upgrade, it will downshift to lower gear till the load decreases and go back to the high gear. Roy
COMMENT by , May 04, 2011
The part of the highway on which it automatically downshifts on me is perfectly flat. I have to drive for about 2 miles before it finally shifts back into the top highway gear. When it downshifts on me, I'm usually going about 60 miles an hour, and my RPM's are a bit over 3200. It's sucking all my gas, killing my miles per gallon.
COMMENT by , May 05, 2011
you may have a bad switch for the converter clutch in the valve body. take it to a trans shop to have them check it for you and give you a bid. Roy