2004 Jaguar XK8 "story tolerance" Questions

...all the story, they just tell you what is out of tolerance - there could be a lot of things out just because one component is malfunctioning, so you need someone who has expertise with this

story with that engine. new engine is in and everything. junk yard said it's out of a 98' neon. when i try to start it, it gluggs like it wants to start but just wont. if i give it a little bit of gas