i got a 03 dodge diesel 2500 5.9 and it is acting like it starving for gas but the check engine lite is not on but i hooked a scan tool to it and it gave me a 623 code

you need to replace your fuel lift pump. it brings low pressure fuel from the tank into the fuel filter bowl. i recommend going with an aftermarket style unit such as a FASS pump

ya that is what i was thinking it was but my scan tool was saying it was a blind code. I dont know it was weird most of the time it will say like bank one rich or something like that

p0623 is low voltage detected at the lift pump. id invest in a new code reader if all it was telling you was the code. But your lift pump is to blame, theyre notoriously bad on the 03-05 trucks because theyre right on the back of the fuel filter bowl and get alot of engine heat. 06-present the lift pump is now an intank style. you really have two choices, go to the stealership and pay them roughly 500-1200 dollars to retrofit your truck to the 06-present style lift pump. or go to Genosgarage.com and buy a FASS fuel pump.