The Cobblers chalked up a third straight Nationwide Division Two win as Vale suffered their first away loss since September.
Some brilliant finishing by home forwards Marco Gabbiadini and Jamie Forrester merely served to further expose ValeÂ’s powder-puff frontline.
Brian Horton's side have now scored only twice in their last six matches.
After Northampton had leapfrogged Vale in the table, home boss Kevan Broadhurst said: “I am absolutely delighted for the players who have worked very hard. That is as good a performance as I have seen from us.” He added: “We have a lot of confidence in our front three at the moment Marco seems to get man of the match here every time at the moment and the way he is playing that is only right and proper.” Gabbiadini's audacious chip eight minutes before the break opened things up and he added his second and 12th of the season early in the second half after Forrester's pass had ridiculed Vale’s attempt to play offside.
Forrester has not been as prolific this season but he sent the home crowd away happy with a perfect finale just two minutes from time.
The tiny striker executed a brilliant trademark chip from the edge of the box which dropped just under Mark Goodlad's crossbar.
Vale clearly have their problems at present yet they fully contributed to an entertaining first half when two long-distance drives from Mark Boyd could have nudged them ahead while the pace of Steve McPhee also caused problems.
An unhappy Horton said: “Our second-half performance was unacceptable and our defending was shocking.”