Bottom line is that you need someone to diagnose it, someone competent. You can collect all sorts of data but need to understand what that data is telling you. If you want to dig into it, do what
@swathdiver recommends and start logging some live data. Check the codes again with a good scanner to see if any are Pending or History codes; not all code readers will see these. Keep a notebook and document the conditions when it happens (after a hot soak, on a cold start, after re-fueling, ambient air temp, etc.) and what you did to get it started.
If changing parts, stick with GM OE ones for the critical sensors. Less expensive aftermarket sensors tend to cause issues and it's worth the $$ to use OE for reliability. Buy from trusted vendors, not Amazon.
Are you describing a slow crank? Or a normal fast crank but it takes a long time for the engine to start?
What kind of fuel is being used? Anything over 10% or 15% alcohol? Any use of E85?
Look a the MAF reading in g/sec at hot idle; it should be very close to the engine displacement in liters (e.g., around 5.3 g/s).
How's the air filter? Is the tubing from the air filter sealed all the way to the throttle body, with no cracks or disconnected air hoses?
What do the hot short- and long-term fuel trims look like, both at idle and at 1800 rpm or so?
There are some other good suggestions given, too, like tryng the clear flood mode when you have a good crank but no start.
Long crank time can be caused by many things (and this likely isn't all of them):
Weak fuel pressure or pressure leaking down with engine off (leaky injector, etc.)
Incorrect calculation of the alcohol content of the fuel (there was an updated GM 'calibration' issued for some engine computers to cure this)
Purge valve on the engine incorrectly allowing fuel vapors to enter the intake, causing a flood condition when attempting to start
MAF sensor mis-reporting
Engine coolant temperature mis-reporting
Defective crank position sensor, or sensor not synced with the cam position sensor (CASE relearn)
Defective fuel pump control module
That's quite the list, but some good live data and knowing the fault conditions would go a long way to get a focus on the cause.