1988 chevy 1500 4*4 with jasper crate 350 engine…?

Got a 350 crate Jasper, a camp that Spunt. . tore set it down in a crank kit, timing chain and sprokets, oil pump, connector cables, etc.. Have they all together and set timing and ran great. . . on my way to stem the engine clean and start all again today, I will down the road its acts like it is running out of gas and the more gas you give it the more it gets worse. . . And suggestions. . in stumped. . Check all my veins, and his timing and all the best. . The 10 high-quality in most of the gas. . In the lost! Thanks