2004 Silverado 5.3 runs fine when idle an runs good up to about 25mph

just bought this truck as far as tuneup the truck runs smooth it only start running bad around 25mph an will not accelerate when I try too

I am with you about changing fuel filter but just would like to know for sure that's it before I spend $500 an that not be the problem

ok Thanks its not a flex fuel an was going to try to fix it myself

well I guess you are telling me to take it to a shop.if I have to buy all these tools I will have more money involved ,I will try something new Thanks

was not the fuel filter or tune up still doing it

TOOK IT AN HAD SCAN DONE JUST SHOWED ABS SENSOR WAS BAD,NO OTHER CODE CAME UP,

mine was doing same thing changed mass air flow and fuel pressure regulator still doing same starts but must crank 6 to 10 seconds, now im going to change canister purge valve pcv valve and remove and clean the electronic throttle body and gasket.