I have a volvo 940 1992 non turbo and sometimes it won't start

I have had this problem with my 2000 Volvo v40 and read on another forum where other people with different models have had the same problem. No one seems to know what the exact problem is or how to fix it. Volvo needs to do something about it, or so it seems to me. It's ridiculous. Sometimes, it will start after 5 minutes and other times it take 20-30 or even longer. The problem is escalating. I use to love my volvo; now I hate it. I have had this problem with my 2000 Volvo v40 and read on another forum where other people with different models have had the same problem. No one seems to know what the exact problem is or how to fix it. Volvo needs to do something about it, or so it seems to me. It's ridiculous. Sometimes, it will start after 5 minutes and other times it take 20-30 or even longer. The problem is escalating. I use to love my volvo; now I hate it.