Had CEL come on a month ago saying camshaft position sensors failure. Went into limp mode, limiting rpms to 2800. Replaced both sensors and CEL came back on with VVT code and low oil pressure code. Took to dealer to not chase parts, said oil pump was bad, causing VVT codes since that system runs off of oil pressure. They said when pan was removed today that engine was full of sludge and needed replaced. I bought at 60k miles and currently have 107k. I've serviced every 3k miles, so previous owner obviously neglected it. In last 8k miles, I've had Bank 2 cylinder head replaced and oil cooler as well. I told them to clean botom end sludge, replace oil pump, and retest for VVT codes. Sound wise?