Jermylawt

I have a 92 c1500 5.7 that I just switched an engine into. I died on me a while back on the highway started spitting and sputtering and within a half mile died would fire and run choppy for a second then die. I thought the computer at the bottom of the distributor went but I knew the engine was getting tired and head gaskets we’re starting to leak so switched out to a junkyard engine with low miles that ran on the stand. Same year make and model just came out of 4x4 instead of 2wd. I’m using my computer out of my truck but when started and running idles very high and seems like it’s getting flooded out and running very rich as soon as you give it any throttle warm or cold. It did run fine on the engine stand. No chips normal idle the whole 9 with the ecm from the junkyard. Could it be just my ecm that is bad and made the old engine die or is it more. Could really use some help thank you