Just bought a clean 2002 Suburban 1500, 4x4 Z71 5.3. On day two, starts having rough starts. It always starts but it sometimes cranks 3-4 seconds before it fires and stumbles to life. Once running, it runs great. Plenty of power that I'm used to with the 5.3.

Where could I begin with this hard-start issue? Before I start throwing money at parts.
Fuel Pressure Regulator? Plugs, wires, coil packs, the list goes on I know to what could contribute. Never had this issue on my 2001 Silverado (had other issues but not this exact one) Just curious if anyone has had a similar symptom ?

 

First check the fuel pressure while running and then see how long it holds with the key off.