why is your MAF disconnected, that could be the known fault, they are there for a reason, if thats not connected it cant tell the ecu how much air is being passed thro, this will make the car run very lean and spluttery, plug it back in, and disconnect the battery, leave for 10 mins or if ya want 30 mins, connect back up and start again, that could be your problem all along your MAF sensor, for a healthy running zetec engine it must have a working one otherwise miss-fires, loss of power will occur