5.7 has the sniffles

pull the valve cover and have someone crank the engine while you watch the rocker arms after unplugging coils.I chased a problem like this it would idle fairly well and as soon as you started accelerating misfire code and cel light flashing.turned out it had the lifter wheel locked up on intake lifter wiping the cam out,it had compression and all the other stuff it needed to run cranking.the almost flat cam would open the valve enough cranking to show good compression,but running it wouldn't open the valve enough to get fuel for load above idle.I found this after I had already pulled the head and put it back together only to pull the head again to change the cam and lifter!!