i would look for timing chain stretch. i've seen them 6 degrees out at 75k miles.

pull both valve covers, zero the crank and see where the cams land. then pull past zero until the cams line up, check the crank. if it's zero, something's wrong, never seen that. 1-3 degrees, there's time 4-6 degrees, think about the chain, tensioner and rails. past 6, do it now, the clock has started.