I was not able to get a Bone Stock L31 Vortec engine using TBI to run correctly with a Bone Stock 1989 TBI Chip!!! ... .... I was able to get a COMPLETELY BONE STOCK Rebuilt TBI LO5 5.7 liter TBI engine with a Vortec Roller Camshaft upgrade to run decent with a stock 1989 TBI Chip. ... Two very different engines!! ... I want to 100% clear, YOU WILL NEED A CUSTOM CHIP for a Bone Stock L31 Vortec engine using TBI!!!! ... dave w