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