How to replace the timing chain and sprocket?

1990 Pontiac Grand Am quad 4 mileage: 100,000. I live in Moscow, Russia. It is difficult to own this type of car here. There are no spare parts or quality mechanics, I have to do all of the repairs myself. My problem is a noise when the engine runs at 2500-3000 rpm. I’m sure it’s timing chain and sprockets, but it’s almost new (about 5000 km). Can you please advise me as to what I need to do to fix this problem?