William Spencer

I have a 2009 Suburban with the 5.3 and 235,000 miles with what seems to be dead #8 cylinder at idle. Took to dealer and second shop, both said they think the camshaft is bad and suggested a new motor. Engine runs rough at idle after about 1 minute of idling but seems to run fine at any rpm above 1000. Question I have is should I replace camshaft and lifters or should I replace motor? Second shop (not dealer) told me about $5K to replace cam with no warranty and I got couple of quotes for motor replace for $8K+ average.