Toyota Repair: 4runner transmission, mom lives, cylinder auto

Question
Hey Ted, I have a 92 4runner,6 cylinder, auto 4wheel drive. It was my mothers. It just turned 200K. It runs perfect was just smogged here in CA (from CO.). When I take off it seems to take of in third gear. If I take off in low and manually shift through the gears it runs perfect. After I drive it on the highway for several miles and come to a stop and start off in D like normal it shifts gears and runs perfect. It repeatedly does this. Every time I start off in low and shift it seems to "warm up" and drives normal until the next day when it repeats.I took it to a transmission shop here in CA (experts) and they said they would have to take the transmission out and take it from there. The toyota dealer in Denver where my mom lives said that "no" it sounds like a sensor that needs replaced. It shifts perfect when warm, shifts to passing gear going  up hills and has plenty of power.Shifts beautiful except when cold. The dash board light on/off OD comes on when cold yet is off after it warms up. What do you think? Can the Toyota dealership here in Temecula, CA make a diagnosis with their equipment. Help, I don't want to have to pay for something other than the real problem. Thanks. David.

Answer
The O/D light coming on on the dash means that there is a diagnostic trouble code(DTC)in the computer, the first step is to find out what the code(s) may be, have the toyota dealer do this.  This is an electronic controlled transmission(ECT) which uses electrical solenoids to perform up/downshifts, in other words the computer determines the shift points based on various inputs from sensors on the engine and transmission.  In most cases shifting problems are caused by a solenoid malfunction.
Have you checked the condition of the transmission fluid? If it looks discolored and dark brown instead of red you can try to have the transmission fluid flushed with a special machine that removes all of the old fluid and small particles that may cause the solenoid openings to become clogged.