They host Catalans Dragons on Sunday looking to build on last weekend’s victory when they nudged past crisis club Salford Red Devils 22-20.
Castleford are sixth having won half their dozen games so far, but are still off the pace that made them such a force in 2014.
They showed the ability to win ugly at Salford but Powell said: “The week before in the Widnes game (a 46-16 defeat) really rattled our confidence.
“Injuries and the team changing is not ideal and we’re still looking for consistency, but I do think it’s a confidence thing.
“We’ve worked on a few things this week to tidy ourselves up and, hopefully, we can climb out of that.
“I thought there were some good signs last week attacking-wise but for whatever reason – good Salford defence or us just missing clinical edge – we didn’t score. It was definitely better, but defensively is where we need to improve versus Catalans.”
Winger James Clare, 24, will play for York City Knights on dual-registration at Swinton Lions this Sunday.
He has scored three tries in seven games but Denny Solomona is set to return against Catalans. The New Zealander has not played since suffering an injury at St Helens on February 27, only his third game since signing from London Broncos.
But Powell, who confirmed recent signing Ryan Bailey will be in his 19-man squad, said: “Denny is available now.
“He’s not played for a few weeks, but obviously Sticks (Clare) didn’t have his best game last week and I’m just looking for him to build some confidence.
“This (York) gives him the chance to play and I think that’s important for him.”