I have a 99 auto suncoast internals as the person I bought it from says the
problem is the tranny keeps gettin hot! Shifts great no slippage but when I get under it the cooling lines are ice cold what could cause this?? Once I get on th hwy it'll cool back down to about 179 or so but if I slow down or idle it'll jump to 230 in 2 minutes???? I am receiving these numbers via edge attitude monitor but when the minute gets 250 the factory trans temp light come on along with the O/D off light??? Any help would be wonderful?? Thank you!!

 

Sounds like the cooler lines are plugged. It could be anti drain back vavle installed backwards or plugged. The cooler could be plugged or a line bent. At any rate the cooler lines should be hot if run for any time. Especially the tube coming out of front left side of tranny.