I need some help. I thought I fixed the knocking issue but it has come back. I was towing our travel trailer back to the storage unit with the gas light on. Just before I got to the gas station the engine started knocking. I filled up and the knocking continued. I got home and checked all the spark plugs and wires. I had replaced all but the front two on the passenger side. So I went ahead and changed those. The knocking didn't start again the next day till I got on the highway. I put a can of seafoam in the gas tank and engine. Problem solved. This was about 3 weeks ago. Yesterday I filled up with gas and picked up the camper to take it to the dealer. No knocking noise. After that we drove up the highway to get something to eat while they worked on the camper and the knocking came back. It gets louder with acceleration. Any ideas? I posted a video of it running idle http://youtu.be/pCpgKNp4vOk I need to get this fixed before our camping trip at the end of the month.