97 Chevy Cavalier running rough

I have a 97 Cavalier, 2.4l, It started running rough friday. No power. Diagnois was random mutiple misfires, and catalytic reading below threshold. I have replaced the catalytic converter, the coil packs, the plugs and wires, had the ignition module tested(it was good)...car still runs rough. Any ideas? I am going to take it and have it tested again, the guy said could be timing chain. HELP!

did you check your vaccume hoses. my uncles 97 cavalier z24 had problem with vaccume leak. even when he would shift from park to drive the engine would make a horrible jerking noise and lacked power. he had scan which said misfires aswell as low bank no. 1. which was vaccume leak.