740 Stalling / Trouble Running

Hello everyone. I am new to your website. I am no avid Volvo fan, I am simply here looking for help from all of you experienced Volvo fanatics. My fiance has a Volvo 740 Sedan. Ill be telling you the year of the vehicle when she gets home. I just wanted to get this topic started. So here goes. Here is the history to my last couple of weeks with our Volvo 740. 1. Car is having problems idling. It starts off as a minor inconvenience. It sounds like an oooooooold jeep. BRA BRA BRA BRA BRA. And the engine rattles hard each time it BRAs. 2. The car begins stalling out on us. At any stop light or sign. Whenever we stop. The car dies. It is becoming increasingly scary for my girlfriend to drive. 3. I find a vaccuum hose that is not attached the next day. I hook it back up. And a mechanic tells me that I should plug this extension up on our intake. Saying it can cause the sensor to give wrong data. And cause your car to not know how much gas to give it. 4. The car seems fine once Ive done both of those things. ( The vaccuum hose and plug ) But then a day later it gets cold out. And it simply wont start in the morning. 5. We bring the car to Middleton's in St. Pete Florida. They keep it overnight. It never gives them a problem. Meaning they can not diagnose the vehicle with their SNAP-ON diagnostic tool. They ran a "Volume Test." And apparently it came out fine. 6. They tell us what COULD help it would be plugs, wires, and a distributor cap. We get plugs and wires done because they were corroded. Cost about 200 dollars. The car stalls out in the middle of a 4-way and this cop gives us a traffic ticket. Another 140 dollars. Ive lost a few days of work due to this. Another 200 or so dollars. 7. Anyway. We get the plugs and wires done. It seems to have HELPED. But in no way resolved the problem. We have to sit up in the morning and start the car up 20 minutes prior to her leaving. And it still cuts out on her at stops. PLEASE. I need your help. You can contact me here. Or by e-mail. ( [email protected] ) Or by Skype. ( Cannabinoid2010 ) Its been the "New Year" for 6 days now and this car has cost me about 600 dollars. And it still needs work. I need some professional Volvo tech help. Please. I am begging.