Noisy 98 intrigue

I drive a 98 olds intrigue, has 83,000 miles, on it. I drive it to and from work, about 100 miles a week. It has started to make a oise that sounds like it grinding or simular. I traced it to the engine area by the firewall of the car. while the car was running, i took off the oil filler cap and the noise stopped. The noise would came back on, when I put the cap on. The PCV valve is working, like brand new (installed last year). Any other areas of concern. Thank you, larry2

Perhaps the egr valve needs replacing and/or cleaning.

I replaced that already, but it is not OE, it came from a parts store (autozone, checkers, etc.). I haven’t cleaned it yet, but I will give it a try. Thank you.

OK, it has been awhile. I found out that, the PCV valve was missing the o-ring. Replaced that and it has been alot quieter, since. Thank you for the help, might need it later.