2001 Dodge Dakota tranny problems

i have a 2001 dodge dakota 4.7l v8 4x4. when ever i shift it from park to reverse an into drive i hear a kind of loud noise. it sounds almost like an accuator i dont really know how to explain it. i got my truck scanned an it came up with 15 different error codes. i hope i dont need a new tranny let me know what you think. Also when i start my truck up the rpms starts jumping from 1500 to about 2000 it even does it when im stopped at a stop light let me know what you think about these 2 problems an what some fixes would be thanks toby