[fp1529]

I have a 99 suburban C1500 5.7 with 150,000 miles on it. Occasionally I would hear a slight tick when I started it, and it was cold outside. The check engine light started coming on about 3 months ago. I had it read at a local auto parts store and it was P1345. The light was intermittent and the truck ran fine so I did not address the issue. Several days ago the truck made a loud knocking noise during a cold start, the noise went away after about 30 seconds, sounded like it was coming fromthe left side of the engine. It makes this noise every start now and does not go away. I have not attempted to start it again because I do not want to damage anything. This sounds like a larger problem than I can handle. I am going to take it to a mechanic. Any ideas on what is wrong? And a reasonalbe cost to fix it? Thanks for your help. Only other thing I have done different is using Castrol High Mileage.