5.7 hemi swap issue

I've swapped a 2005 5.7 truck motor into my 66 coronet. I am having trouble getting it to run though. The motor turns over and starts if I use a blast of starting fluid but it only idles roughly for about 20-30 seconds then shuts off. I think that it might be an anti theft issue but I was told that the anti theft shuts it down faster than that and the computer that I am using is from a 2004 5.7 truck with manual transmission. I was told that the 2004's didn't have the anti theft. any ideas? I did check the fuel pressure and I am at about 53+/- psi. I am using the corvette fuel filter regulator and a walbro in tank fuel pump

Just a possibility do you have power to the computer when in the run position. Found that I had a bad ignition switch, put new switch in a connected both the start and run wire leads together and took care of problem.

anybody else got any ideas?

pretty sure SKIM theft system can cause a start and die. Usually, they start and die 5-6 times, then nothing at all ( i think). The only way to know for sure would be to use a scan tool to see if the theft system is indeed activated.

I dont think, 04 computers did not have SKIM just because it was an 04. Or use an anoid light to check and see if the injectors quit pulsing when the car quits running.