Ah, yes,
that level. It's a real bitch, yeah. There's this one jump that always got me as a kid - it's at the tail end of being chased by three boulders in a row. You have to do this jump at the very last minute, but because the platform you're jumping off of turns to bright orange on the far right, where it overlaps a bright orange background, it's hard to tell - so I always jumped early, and
always got nailed by the boulder as a result. Once you get past that boulder, it's a little more sane.
Here's a video of a guy playing it without dying at all. Reference it, I guess.