hi i have recently converted my 1.6 cvh engine mk4 orion to a 1.8 fiesta zetec engine using the fiesta ecu and loom wired into my own loom car starts fine but as soon as the engine warms up and you try to drive it it starts splutering and losses power to the point where it hardly moves when you press the accelerator to the point where it tries to cut out help me please