Howdy fellas, im new to the forum and was looking for some advice.

I have an old client who is ready for me to take a look at what may be wrong with his 2002 cavalier (2.2 LS i believe). Im Scheduled to go over in a few days and begin diagnosing the problem. as im not new to knuckle busting but have amateur skills at diagnosing id like to see if you guys can offer some key points to explore on my initial visit.

Symptoms:

the engine runs very rough and has no power under acceleration. there is also a mechanical chattering that is consistent with the rpm of the engine, the owner suspects that it is valve related and i tend to agree considering the lack of power reported. i suspect a chipped valve(s) or possibly overly worn valve seats. the engine has over 200k miles and has been sitting for around 18 months. I have not yet had the opportunity to view the engine running or starting, but ive already determined that the gas tank needs to be drained.

My plan:

To pull the cam cover and inspect the lifters and cam timing gears as well as the timing components. I also plan to pull the Head and inspect the valves and head gasket. I will then consult with the customer and go from there.

Any other thoughts that you guys could leave me with would be greatly appreciated.

Thanks!