Hey guys im new here i have a 97 k1500 with the 5.7 vortec. Having a major lack of power issue with motor. Ive changed the following. Cat converters ( hi flow 400 cell converters) tps sensor, cam shaft sensor, plugs wire distributor cap and rotor button fuel filter cai. In hopes that power would be restored but still having same issue. When easing into throttle runs fine upon wot throttle stubbles hesitates backfires.. Got 1 o2 dtc for b1 s2 hi voltage changing tonight but doubtful it will work motor has 18k on gm goodwrench crate engine. Before issue motor ran fine with plenty of power and the lack of power slowly came up.. Fuel pressure is 55-63 psi at idle and when warm and giving throttle

 

Also when engine is up to temp the issue gets worse with no dtc codes set other then o2 sensor code