Won't idle
 

I'm to the point in my conversion where I'm trying to get the engine to run in the chassis. It runs fine, but it won't idle. The RPM drops very low and then it dies. It revs fine and runs fine off idle

The engine is the 5.3L LM7, 2003.

An LS1 intake and injectors were installed to get the hood clearance I needed for the Jaguar I put it in (the LS1 injectors flow about 3-4 lbs per hour than the truck's injectors)

Rail pressure is set at 53psi and I've tried lowering it a little to compensate for the higher flow injectors, but it didn't seem to make any difference

I'm using the truck's electronic throttle and MAF. All of the PCM and electronic throttle stuff is off the same vehicle. I had my tuner delete the VATS so I could drive it to the dyno facility, but that's all that's been done to the PCM.

Is there an idle relearn routine for the truck PCM?

Any suggestions on how to troubleshoot the low idle issue?