I had this problem last year ... 3 different (pro) mechanics told me I needed a valve job. They were wrong ... somehow I knew that ... then I finally found a "real" mechanic who's into the old-school stuff. He came over the house, put a large screwdriver against my fuel pump and said, "Listen to this."
It was the fuel pump! A few bucks and some 30 minutes later, I was driving around with no more knocking sound and a
huge sh*t-eatin' grin on my face.
