Well I wish I had an answer as I've been chasing this since last summer. I see the timing being pulled on my scanner, my cam and lifters didn't fail but I tore the engine apart to find this hesitation problem. When I put it back together I put the new cam lifters and pushrods, valves and rockers in I also changes mds solenoids in.
I put the stethoscope on my left knock sensor and it matches the tick exactly. I'm trying to believe it's not internal but running out of Hope.