99 Buick Regal Shuts off on me after being drove for more than 10 miles and several other minor issues?

I have a 99 Buick Regal. Shortly after we purchased it, it started having problems. When you drive it for a period of 30 minutes or longer, and usually when it's hot outside, the car will shut it's self off, no warning. If you start it back up immediately, when you go to drive, it acts as if it has ran out of gas and will shut off again. It's un-drive able. After it sits for 30-60 min. you can then get back in it and drive it again, just perfect. What in the world could this be? We put it on a diagnostic machine and it said that the catalytic converter was clogged and that the torc converter was stuck open. Sometimes, before it started shutting off, when you would drive it would kind of hard shift, but it felt more like you were running out of gas then a transmission problem. We put some stuff called Lube Guard in the Transmission, it's for torc converters, and now the shifting issue has stopped but it still shuts off on us, how can we fix this? Also, all of our digital dash is out, what could be the cause of this? And we have dual climate control (pass/driver) heat and air feature and the driver side blows out heat all the time but the passenger side is changeable from heat to air, what could be the cause of this? Also, the heated seat feature only works for the passenger seat, why would the driver side be not functioning correctly? Well, I know this is long, but I would really appreciate all the help I can get. I need this car to be reliable and I can't afford to take it to a mechanic. I just don't have the money. I hope someone can help, all suggestions will be greatly appreciated. Thanks and have a wonderful day!!! God Bless, Amberlynn