Cobblers gritted their teeth to get back on the winning trail with three hard-fought points against Paul Tisdale’s relegation-threatened team.
But despite retaining second spot in Sky Bet League Two, McGowan was far from impressed by the way his side saw out victory.
Cruising at 2-0 up, Town became complacent in the final 20 minutes and by full-time they were clinging on to all three points after Chris Lines pulled one goal back.
Jon Brady’s side have now conceded five goals in the last three games, all of which have come in the final 15 minutes.
“We need to start learning because when we are in a winning position, you can’t just go on cruise control,” said a displeased McGowan.
“Obviously it’s great that we got the win but there are plenty of learning curves which we need to work on.
“For me, the last 20 minutes were not good enough, but we can’t get too downbeat because it’s a great three points away from home.
“How many people are this stage of the season are bothered about the performance? It’s the business end and it’s all about the result.
“We’re keeping ourselves in the hunt and that’s the most important thing, but we have to find ways of not sitting back and thinking ‘this is easy’ because it did feel easy for the first 25 minutes.
“No disrespect to Stevenage but we allowed them back into the game and they scored because of what we did so we need to learn from that.
“But it’s the business end of the season, we scored a couple of good goals and came away with the points.”
Asked specifically what the Cobblers need to work on, McGowan added: “It’s just different things and it comes from the defence sitting too deep, including myself, because they aren’t hurting you, and it’s about the attackers as well – can you keep the ball and make it stick for us?
“There’s also lots of little headers around the pitch and ultimately, it ends in them scoring a goal. We just can’t keep doing that.
“But I’m not going to stand here and be downbeat because we have scored two good goals and the points are so important and I’m made up for the fans who travelled in their numbers again.”
McGowan set Cobblers on their way at Stevenage with a sensational early strike.
Louis Appere’s flick from Bez Lubala’s cross looked to be heading away from danger until the fast-arriving McGowan came steaming in and unleashed a stunning half-volley which zipped into the bottom corner.
“As soon as it left my boot, I knew it had hit the sweet spot,” said the full-back, who has two goals this season.“Sometimes you just know and I knew straight away but it’s more about helping the team. People will say it’s a good goal but I’m just happy we won.”
McGowan’s sweet finish came right in front of the away fans and was reminiscent of Ricky Holmes’ famous stoppage-time winner at the same end in 2016.
“The fans have been excellent this season and we can’t thank them enough,” said McGowan.
“They always travel in numbers and get right behind the lads and we are going to need them in the run-in because we have a few big away games and we have another big game on Saturday.
“We will put this one to bed, take the three points and move on, business as usual.”
Next up is in-form Bristol Rovers at Sixfields.
McGowan added: “We know it’s a big game for the club and hopefully the fans get behind us because Bristol Rovers are going well.
“But frankly I don’t really care about them because it’s all about what we do at this stage of the season and we will put the onus on us to play on the front foot at home and give them a good game.”