Yes, I agree with Steve, it’s a 1998 Muni Mula, size 16, and I’d guess it should weigh just about exactly 4 lbs, does it? It’s made of ‘custom-butted’ 7005 aluminium, takes a 27.0 post and a 31.8 front mech. Kona said it was “Our hardtail bike for fun and technical single track riding.” It was available as a frame only, and my recollection is that it was £299.
As you can see from these photos, it has exactly the same dropout as this 1999 Muni Mula, but it can’t be a 99 as it lacks the down tube gusset. But it can’t be a 97 either, as they didn’t have replaceable dropouts. So that leaves 98 and as the 98 MM was polished that's probably why it lost its decals somewhere along the line. I can’t understand though why anybody would file off its serial number from under the bb – are you sure it isn’t just faint?
And yes, I’d say it’s a very good frame, and very well worthy of being rescued. You could probably get new decals made by Gil_M on this site and turn it into a very nice late-retro cross-country/play bike. As it happens, I have a pair of 98 Bomber Z2 Lights that would be perfect for it, but unfortunately they’re not for sale!
I hope you get it up and running.