S10 4.3 bogs off idle

1999 S10 4.3/4L60E with marine MPFI intake manifold and SyTy exhaust manifolds/turbo. Needless to say, the air intake tract is completely different from the stock configuration. The truck has a bog off idle; I cannot mash the gas too quickly or it will backfire. While cruising, I don't seem to have any bog problems.

Some other items to note, in case they are helpful: Removing the TM from the trans relieved some of the bog. When the truck warms up, it relieves some of the bog. However, it never completely goes away. Something needs to be adjusted.

Which table(s) should I be reviewing to adjust this? Any hints on how to determine what to change?