Possible tranny problems... NEED HELP

Ok, it has been a while since I've posted anything on here. But when I have a problem with a vehicle, this is where I come...

Problem: When I go to take off in the mornings (or if I haven't drove in a little bit) my truck is VERY sluggish, almost like it is in 3rd gear already, or like I have the parking brake on. But I can put it in LOW and it starts off fine, then I'll just put it in drive after I'm going. This has been an on-going problem that I have been avoiding because I really do not want to it to be the trans. I've tried doing some research but haven't found any solutions. The closest thing I've found is this... This is the same problem I've been having, but as you can see, it doesn't help much.

Thanks in advance

 

a) sounds like rear brake shoes stuck to drum

pop off wheels inspect drum brakes and assembly

check for leaks of brake fluid or axle seals

check parking brake pivots (bellcranks)

b) could be transmission. check radiator for oil, and atf for foam or water

c) check all cables on throttle body and take out any slack in throttle
cable, cruise control, and transmission kickdown cable

 

Thanks, I'll check the trans cable in the morning. I doubt it's the brakes because I can put it in low and it takes off fine. I wonder if anyone else has had this problem