"Motor Control Systems Failure" sonuds rather fatal but it can mean any number of literally hundreds of things.
its the equivelant of an engine management light which means some sort of fault code has been generated, the trick is to get the fault codes read to determine exactly what has been generated.
if you have a laptop then you can buy a KKL USB cable off ebay and with a free version of FiatECUScan should get you going and have you sorted with the fault codes.
once you have the fault codes we sort you out a little easier.
typically most people without a fault code would recommend that you start with the MAF if you are having fueling trim issues and power issues.
good trick with the MAF meter is to unplug it and go for a drive - the car won't idle well with it unplugged, it may even stall, but if it drives much better then you have your answer right there.