Fault codes p0300, p1343, p1345, p1347

What is your question?

This car has about 120k, it is still getting decent gas mpg, but stutters as if just running on a few cylinders. I replaced plugs and valve cover gasket about 3k ago. I can not detect any leaks in the intake and I really don't want to send the local parts guy on a vacation while I'm throwing parts at this thing. Help