BMW: 1989 BMW 325i-Engine cutting out at operating temperature, bmw 325i, temp gauge

Question
I have a 1989'BMW 325i 2.5litre. It idles and runs fine, but once it reaches normal operating temperatures the engine starts shutting off.  This happens at lower RPMs/speeds when in first and second but also at higher speeds when i'm cruising around,45-60mph as well.  I was told that the O2 sensor needed to be replaced but also that my computer was bad(I had other worked done at a shop recently). I get the red check engine light which flashes on right as it's cutting out.  Any opinions?  

Answer
Thomas,
 These cars have a "thermo-time" switch that is located in the thermostat housing next to your temp gauge sending unit.  This sensor tells the computer when the vehicle is up to operating temperature, and can turn off the "cold-start" function.  Some times this sensor sends faulty signals to the ECU telling it that the car is too hot, or something similar.  If you replace this it should fix the problem.  "the ECU is bad" is the most common answer you will get from a shop.  If you go in there with a tire out of balance, I bet they would tell you the computer needs to be replaced.  Anyhow these guys dont know what the problem is, and dont really want to spend alot of time trying to fix it (time = money in that business) so they just spit out what they think will help.  Usually this will cost alot and take alot of time to fix (money for them).

 Good luck,
 Josh