i have a 98 silverado 5.7. it dies at low rpms or if ive stopped but usually only if i drive it shut it off and let it cool and drive again if turn the key off and try starting it again it starts right up. it will either stutter like the pumps been shut off or shut right off like the keys been shut off. ive replaced fuel pump relay filter lines from pump to filter oil pressure switch checked fuzes and grounds i feel like it might be the ecu cutting power to the pump any suggestions would be greatly appreciated