I'm trying to help out a friend with a Grand Prix...same motor as a '97 six cylinder camaro. It threw a code for "misfire cylinder #3." It surges pretty bad above 4000rpm under load, but not in neutral. It will consistently throw a code every time the surging occurs. It seems to idle fine, but the valves seem a little loud. I know that the valvetrain on a z is a little noisy, are the 6's noisy as well. With the engine shroud on, the hood closed. and all the windows closed it's hard to notice so I think it might be normal. I'm not familiar with these motors what should I check out first? She's talked to people who have told her it's definetly a valve or lifter, but I told her to check out the cheaper things first before digging too deep. Thanks!

 

Check the plugs and wires. A burned wire was what was wrong when the same symptoms happened to my car (96 Firebird)