My tahoe has extended cranking issues after driving around and letting it sit for about 25 mins or more. When it happens, sometimes it will crank for an extended period of time than turn over or take 3-4 tries before it fully turns over. First start of the day, it turns over like a brand new vehicle. So far the fuel pump, fuel pressure regulator, fuel filter, coolant temp sensor has been replaced. A fuel pressure test has also been done and each injector removed to test and my mechanic said all was in specs. So we are stumped, and I'm tired of throwing money at it. Any clues?