Hey I have a 2001 2nd gen 1500 5.9 4x4. It is slow to take off in drive like it's not in low gear but when I put it in 1 it pulls off just fine. No problems going through the other gears other than it doesn't seem to want to go into low gear in drive.

 

Different hydraulic circuits in use between the two conditions. Your trans is in limp mode. Get it scanned for codes.