[Tech II]

Yes, it will help to know the mods, and how long after the mods, did the misfiring start.....

This has to be a late model 3.8, to have a O2 sensor on each bank.....however, P0171 is not setting, which means the misfire is on Bank #2(2-4-6).....

Since the misfire is bad, it is causing the CE to flash.....even though you have changed coils, wires and plugs have you checked spark output, with a spark tester?

Since it seems only one bank is affected, I doubt it's a MAF problem(this can be checked though, just by disconnecting the MAF and see if the problem is changed)......also, I doubt it's a fuel pressure problem because both banks would be affected....

I have seen problems with the gasket between the upper plenum and the lower intake....it could develop a crack in the gasket, and during an accel, could be leaking air in either cylinder 2, 4, or six, causing a lean condition in that bank.......sometimes it can be detected by spraying carb cleaner around the base of the upper plenum......raise rpm's until the misfire starts and then spray...if misfire goes away you have found your problem.....sometimes, the leak may be more subtle, and you will have to observe the O2 sensors while spraying.....

Other possibilities are an exhaust leak on the bank 2 side....

Bad O2 sensor, or harness problem....

Could also be an injector problem on bank #2 side.....

Rare would be an PCM problem......also check for a rodent problem eating harnesses.....