Hello. I ran into some weird problems yesterday and today. While I was driving I noticed a sulfur smell coming from my exhaust. My mind jumped to my catalytic converter going back and that I needed to go get it checked up on. However, driving today I noticed while idling with the AC on I would hear a tick noise from the engine bay and then the rpms would jump and hold before coming back down with another tick noise. I am unsure if these issues are related but I just wanted an idea to see what was going on or if anyone had something similar happen. I drive a 2003 2.4L Frontier manual. I don't seem to be getting any worse mpg but I haven't really calculated it and I also can't really tell if there has been a loss in power. Thank you!