wrong mate! in the early days ford used champion sparkplugs which had major running issues due to the 1.3mm gap , ford then started using motorcraft plugs with a 1.0mm gap which it has stayed at ever since , the haynes manual is well out dated so 1.0mm is right and 1.3mm will make your car run like a bag of shit, as for the running fault is your engine timed up correctly? , could be a lambda problem as i got a scrap one and it idled very poorly , cured since fitting a new one .
hope this helps cheers paul