Hello, why did they come to the conclusion that it was the computer? You should try first scanning the car and to discard other sensors according to the codes, such as temperature for example, check its resistance and compare it with a table you must match you inside tolerances, you find it here in the Stratus manual.
Look at the starting problem is generally because of the cycle or motor temperature sensor, you just change it, do not look for another because it has no temperature bulb so it will not be a problem to find it.