2003 Altima 2.5 won't shift until it car runs for 30 mins

I have a 2008 Nissan Altima 2.5. I bought it less
than a year ago with a bad transmission and had it
replaced with a low mileage transmission from
Japan when I first got it. Now all of a sudden it
won't shift until the car warm up for about 30
minutes and then it drives fine. If I don't let it warm
up and have it in drive it will immediately shut off if
I put it into drive or reverse. I'm super frustrated
because I've already spent a lot of money and I'm
told the only way to diagnose anything requires
dropping the subframe & transmission again. Help!