It's a 99, v6

Whats the average price to get one of our transmissions rebuilt???

My question is when it is cold outside n i drive my car for the first like 5 mins my car won't shift into the final gear in OD, n also driving on the highway if i let off the gas when going around 65 the rpm's bounce up and down a couple hundred rpms,

also my car when driving down the road with the windows down in second gear between like 2500 and 3000 rpms it sounds like an air pressure leak or sumthing and sounds like air blowing out of somewhere

if anyone could help me to find the reason y my car does this it would be a big help, it is an 99 avenger es v6
thxs everyone