Toyota Repair: 95 4 runner, strange coincidence, perplexing problem

Question
I have a 95 4wd, at, 6cyl that when cold seems to be stuck in 4L. In the mornings the trans shifts quickly to 3rd and then stays locked there for about 7-10 minutes while only being able to do about 35mph thens chugs and for the rest of the day drives ok.I have tried plugging the front diff vac lines, checked the hubs, t/v cable, serviced the trans, checked the vsv valves, checked coolant sensor & thermostat. I can let the vehicle warm up while shifted into 4L and everything works ok. The colder the outside temp the worse.
thanks for any help

Answer
That's a strange coincidence because my 1990 Runner started to do the same thing a couple of years ago and this is the first time I have ever had this question come up, it was only in the cold season that it would do this and it was at random but quite frequent, it drove me nuts because I had to get to work and get on the freeway but it would not come out of low 4 until I drove around for a awhile, about five minutes and then it would come out of low 4, I also tried a few adjustments etc but it still did it, I even thought of replacing the ECU or the transmission but in the meantime I bought another toyota and decided that the old 4 Runner had seen better days and only drove it on weekends to do some off roading and the problem did not happen in about two years but it was used very infrequently, short of replacing the computer or the entire transmission I really have no other advice for you, I ended up selling the 4-Runner to a guy at work real cheap but never resolved this perplexing problem,sorry can't be of any real help but at least you know that your'e not the only one that has this problem because up until now I thought I was. Try logging on to JustAsk.Com, I'm a member there, I'd like to see what some of their responses may be.