temp sensor casuing slow shifting when cool?

[EyeTalk2Trees]

I just can't figure it out, my trans doesn't want to shift out of 2nd gear untill the motor warms -up. First it was around 100F now over the last 2 months it has slowly krept up to 180 before shifting. I bought a coolant sensor(not the one that goes to the guage) only because a friend suggested that this helped his GN, something about the computer reading the temp correctly. The part is only $16 so i thought i'd give it a try. Once the motor/trans is warm it shifts fine, nice and strong. I even put that lucus trans additive and it didn't help. I've replaced the filter and fluid about 10k miles ago(if it was even that long ago) and i put sinthetic fluid in, I'm alittle parinoid about this car, it has a lot of miles and I am in college, so i don't have any money to fix it or any place but the curb side to work on it. majority of my tools and shop are 600 miles away.

if anyone can help thanks

sorry so long

 

[HOTTOGO]

The only thing I can think of that the temp sender would effect is the tc lock up, it has to be at operating temp for ecm to tell it to work. As for the no 3rd shift cold, it will not shift period at any throttle position, 1/2, 3/4, WOT or letting off after WOT? Maybe 2-3 shift valve sticking until it warms up?