Chevrolet Repair Questions? Ask a Chevy Mechanic for Answers ASAP
Hello! My name is Gary.Welcome to JustAnswer.I'm reviewing your question now, and will post back with a reply shortly.
Does your engine have AFM, goes from V8 to V4 for highway?
If so, Cylinder 7 is an AFM cylinder, and sounds like a roller lifter has rotated in the block.
Do you need any further help?
I hope my advice has been of assistance to you.