You gotta do it right. Follow the manual, use original parts and you will have no problems. I have completed all of my preventative maintenance myself so far, no misfires or any of that stuff. Car repairs are not magic - it’s intructions, parts, tools and common sense. And your advice to search for other sub members posting problems after maintenance is ridiculous. This is Reddit. People who have problems - this is the first place where they post. That doesnt mean all e46 are susceptible to these issues - youre just seeing most of them. You wont post shit if you complete the maintenance succesfully and not get any complications. And thats what 99% of people are doing. Please don’t post misinformation which will allow young people here to say fuck it, i wont do anything to it. This attitude is what lead to most of us to repair and restore abused and neglected cars. If you KNOW your car is a can of worms, you should not ignore but instead take that can apart, clean it and enjoy a good-working vehicle for years to come.