primativesniper

Engine in my truck went out couple months ago. I took out original 5.7 tbi and replaced with a 72 5.7 fresh rebuild with mild cam, edelbrock performer intake, and headers. I retained but replaced all original sensors along with tbi on new engine. After getting engine in truck it don't seem to idle right. Seems it may be running a little rich, it runs alright on road till I slow down then stop it idles rough then dies?? Any ideas guys? Can use and appreciate any and all ideas please???