5.3 swap wont run correctly

[Caleb]

my 5.3 out of an 02' 1500 will start and idle around 400 RPM for about 30 seconds before it dies. i have no clue what is wrong. took it to 2 shops both dont know whats wrong and they refused to work on it said it wasnt worth their time. so instead of wasting time with other people im gonna finish this thing myslef. i have 51PSI fuel pressure. got new intake gasket because it failed my smoke test. i thought it may be a bad MAF sensor. it backfires through intake a little and the plugs look fouled. got new ones and when i get it back im gonna swap it out. it has a p0030 trouble code. also according to the shops the STFT and the LTFT dont log at all they stay 0%. builder said he gonna reflash a new PCM and send it to me to rule that out. i could use some serious help. thank you.