Having with trans up shifting someone please help

:mad:This is an intermitten problem most of the time it will shift with no problem but after it is warmed up on longer drive times it will stay in a lower gear at high speeds sometimes first and sometimes second and this is when I am doing 50 or 60 miles per hour. Then when I stop for a short time it will stop doing this then starts again. I've had Chrysler check out the transmission out and they said it is fine. Can anyone help me. I have a little time left on my warrentee as I bought this 1996 LXi with 3.8 used and have had the used car dealer work on it with their transmission shop they had for three days then returned it saying it was fixed. But the very next time I took it out on alittle ride it did again.
:banghead: Please help this driving me crazy, digimon

did they tell you what they fixed?????
the problem as described can be the start of a internal part failure////
or controller problem. a live data scanner would help to show what
is going on /// intermittant problems are a bitch both from the customers
view AND the tech's view !!!!! good luck
gbaum

Just an update on my shifting problem. The first time that I had brought the van in to be repaired and he gave it back to me saying that it was repaired. The very next time that I drove it, the darn thing did it again. So I knew that the problem had not been resolved. By that time I had read every post in this forum on mini vans like mine (Chrysler Town & Country, Dogde Caravan and Plymouth Voyager). Any time that their was a problem like mine there was a mension of the "speed sensers". Soooo when I took it back to him the second time I sejested that they may need replacing. Then he said that his trany guy already checked them and they were fine. So I told him that they only cost about $30.00 each and were farely easy to replace. Well when I left the van there he didn't say if he would or wouldn't replace them. In two days he calls me and says to come and pick it up that it was fixed. When I picked it up I asked him just what he did to it, and he says that they replaced the (speed sensers). Well I just got back from a three hour drive and it shifted fine everytime. As you may have guessed I am now a happy camper. I would like to thank (trannyman52) for his reply on this matter, and for the advise from any of the other posts on this problem that had been posted previously on up shifting. Without them I may still have been in that very unsettiling position, "First Gear".
Thanks Again,
digimon