Ok, I'm at my wits end. Here are the details:

Bottom Line UP Front: I cannot resolve low idle issues -- 2003 Suburban 1500 KT Flex Fuel

I have done the following:
--> Replaced Air Filter
--> Replaced the MAF Sensor
--> Replaced all plugs and wires
--> Replaced Fuel Pressure Regulator
--> Replaced Throttle Body Intake [TBI] (a.k.a Air Intake Manifold) - TPS is included in unit
--> Replaced TBI gasket***
--> Cleaned as much of the air intake system as I could

*** I replaced the TBI gasket after getting engine code P0171 and P0174 - System Too Lean (bank 1 and bank 2, respectively). I have cleared the code and it does not come back up; however, I still have idle issues.

My symptoms:
- After initial start, approximately one minute (or less) the engine begins to idle low, rough and sporadic - but not to the point of stalling. Driving for approximately 5 - 10 minutes to warm engine to 180+ degrees, the idle roughness is significantly lessoned at stops. When in park, after driving and truck at operating temp, it takes about 30 sec to a minute when some rough idling occurs.

I do not get any codes that indicate cylinders misfiring but I do not know if this could be an injector circuit malfunctioning or some or related issue.

Any thoughts or insight would be GREATLY appreciated!