02 5.3L Swap Random 3sec starts. (pulling hair out!!)

[MEANDEAN]

I put a 02 5.3l in my 39 Chevy. Motor won't start. The vats is set to none and shows pass. I have been screwing w/ the tune all last night and today. The motor fired up once last night for less then 3 secs and again twice to day for less then 3 sec.
PLEASE HELP!!!

Motor is a 02 5.3l out of a Tahoe
Pcm is out of a 02 1500 5.3l
Harness is a SSP

[MikeOD]

Post up the tune.

[socal99]

i was having a similar problem on a swap it was a bad ground to the frame