I have a 2006 sport with a 3 litre, 5 speed manual that I've been chasing down this rich bank 1/2 problem. Back story is I bought it with CEL light on knowing that something was wrong, didn't run too bad but you could tell it a little misfire. Forscan showed misfires on 5 and 6 cylinder and some 02 sensors not switching correctly. Truck has 260km on it so no surprise. I did the usual stuff to remove the obvious possible causes of the misfires and rich codes coming off the O2 sensors. New plugs, wires, air filter, clean mass airflow sensor, replace all four O2 sensor, replace IAC, camshaft synchronizer. Test and confirmed that coil pack was fine but still had misfires on 5 and 6. Checked the injectors for function while running, all click fine, WOT test no attempted startup, check fuel pressure which 65 psi, etc. So I resigned myself to the fact its probably the bad valve/seat issue, which turned out to be recessed valve seats (known issue) and just old O2 sensors
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So ordered some reman'd heads and injectors, installed them and now consistently throws the P2196 and P2198 codes, and upstream rich bank 1/2 sensor stuck or not switching correctly. Before the new heads and injectors there was no P2196/2198 codes. Even replaced the mass air flow sensor and it was reporting 5.8gm/s at 750 idle, seemed kind of high. New one is better but didn't make much difference. IAT temp was spot on with ECT at startup so that wasn't it. So what I'm thinking is that I maybe got sent some "aftermarket" flex injectors (22lb) rather than the 14lb gas only ones. Always rich and STFT and LTFT all -30 or very close if I drive it long enough, pulse width is ~2.4 ms at idle. From what I've read idle with 13/14lb injector should be between 4-8ms at idle. Well and now it has decided that it wants to idle high too.... The PCM is trying real hard to trim the fuel flow but can't bring it down enough at low rpm...

Looking for a sanity check before I pull the easy bank of new injectors out and put in 3 of the high mile originals. Maybe that will cure the P2198/2196 codes or at least on bank1 ???

Attached a pic after a KAM reset and a very short drive. 10 mins highway, 10 in town.