trany going in to limp mode

[ave8tors]

from thrid to over drive if you have your foot half way down on the pedal or a good load when the truck goes threw all the gears they are pretty close shifts then from third to overdrive it goes from 3k down to 2k and puts a good load on the engine but if you go to pass some one it will kick down then go to limp mode after couple of seconds. this is one way it is acting another is if you put your foot to the floor from a stand still it goes threw the gears then check engine light comes on checked it out reading "low fuel pressure rail" could this make the trany act the way it is?

[ave8tors]

so i figured out today from reading post and trying different things, my fuel flow remains at 170 at stock mode and the truck runs fine, when i tune it on any setting when you get into it the fuel flow goes to 170 then drops off to 130 resulting in "low mainfold fuel pressure" so im assuming that it is my tuner which is superchips. any ideas on how to fix? im emailing superchips today and see what they say