Why won't my truck move when cold ? It's a 2000 year model

My vehicle has to warm up for 10 minutes before I can get it to move. When cold it will only move if I riv  up the engine to 2500- 3000 rpm . After the engine has been running for 10 minutes ,  or more it will move when I riv the engine up 700 - 900 rpm. Once I start driving everything works as it should. No slipping , no hard shifting or anything. I checked fluid level while hot , and in park . Fluid level checked full . I'm stumped !