Victory over Oldham put the club in the FA Cup quarter-finals for the third time in five years, and despite one point from nine in the Premier League they remain sixth and in the hunt for a European place.
Howard is one of four senior men - along with Leighton Baines, Phil Jagielka and Leon Osman - to have started every league game, and Everton have used fewer players than any of the five teams above them in the table.
"Let's hope we have something in reserve," goalkeeper Howard said. "We spent a lot of energy early in the season and now it's just about our big players.
"The teams around us have the ability to chop and change their team on a given weekend and still have a lot of firepower.
"At the moment we don't have that so it's just going to be about our big players who have played a ton of minutes to keep producing until the end of the season.
"I don't think we're firing on all cylinders but at the moment but I think it's a good thing - we've advanced in the cup, we've got a home draw and when you look at the league table we're still in the thick of it.
"We're going to have to start doing the business but we're still there. I feel like I'd rather not be firing on all cylinders and be where we are than not."