03 Suburban, 5.3L flex fuel, Low Oil Pressure issues, need help
 

Thanks for looking. I have an 03 Suburban with 185k miles 4wd selectable. Owned for a year and have changed valve cover gaskets, intake manifold gaskets, lower valley tray gasket, rear main seal, oil pan gasket, oil level sensor, oil pressure sending unit(3 times), and all fluids changed. We have had an issue the past week with the oil pressure dropping to between 0-5 at idle. This trips the DIC low oil level, turn off now. We changed the OPS(AC Delco this time) unit and did an oil change/filter last night. I drove it hard and all seemed well but pressure at idle was between 5-10psi. Even at start up, the pressure never went above 40. My wife was driving today and at a stop and at idle, the same warning came on. We don't hear any noise or issues either. I'm trying to wrap my head around all of this. Am I looking at an oil pump and pick up tube replacement? Could it be something else? I plan on getting a manual gauge tomorrow, but I'm not expecting miracles. I have read that the PCM will stop spark if the pressure is 0, but our engine never stops. The only time we have ever had the motor die is while in reverse, at idle, and turning the wheel to parallel park it occasionally stalls out. Not sure why though? Any ideas? Any help? Thanks so much.