Aside from the inherent difficulty of a level, video games can induce significant tension through music alone. Anyone who's experienced the anxiety of trying to prevent Sonic the Hedgehog from drowning will attest to music's ability to ratchet up a video game's intensity.
At the same time, music is also remarkably malleable. A song that has garnered a reputation for being tense and ominous can easily become calming with a shift in instrumentation and key. For example, transitioning a song to a minor key can drastically alter one's perception of the track, irrespective of one's previous associations with it.
In Donkey Kong Country, Fear Factory is a pretty tough level with a memorable soundtrack that can presumably elicit a pavlovian sense of dread for anyone that grew up with the game. However, the jazzy rendition of the Fear Factory theme featured above, produced by the Consouls' YouTube channel, might help you reframe the theme positively.