regardless of engine 3.6 or 4.0, the Down stream O2 isn't needed, just the Upstream O2
The only Chrysler PCM to actively control fuel pressure is a Hellcat/Demon.
So that TJ 4.0 pcm should expect a static 55-58psi at the dead head fuel rail like most Chryslers.
The easy way to regulate fuel to to a dead head fuel rail is either
1. Holley Drop in pump/regulator assembly
Holley Sniper EFI 12-319 Holley EFI Fuel Tank Modules - 255 LPH - Mopar A-Body
2. Use Tanks Inc Fuel tank + a 97-2000 Corvette Fuel Filter which has its own regulator already set to 58psi
