Auto tranny problem
 

A buddy of mine just got a 99 4x4 dually with only 80 thousand miles on. Truck runs great except if you try and take off in drive its got next to no power and with his ski boat hooked it won't move it's not slipping just has no balls. Drop it down and manually shift it and it runs like a champs. With no trailer it'll go if left in drive but drop it in first and take off it'll roast the tires. I'm lost can't find any info everything iv read says boost problem or fuel but I don't see how when it acts just fine when manually shifting. Help please!!:argh: