I have a late 90's Kona Lava Dome. Picked it up a few weeks ago. It's a great bike. It needed a good cleaning and the chain, chainrings and cassette were worn out. By the way, it's a 3X7.
I put a new Sram 12-32 7 speed cassette on the bike. A new Sram 8 speed chain followed and I replaced the old crankset with a Shimano Altus unit (it was cheap, cheap, cheap from Nashbar and the bike isn't exactly new). The installation and set-up went well but shifting from the middle to the small ring can't be done under load, or for that matter, when pedaling lightly. Upshifts are no problem and shifting from the big to the small ring also goes well. I've done some tweaking and am able to get the middle to small ring shift if I'm not cross chaining to any great degree.
Shimano specs a 123mm bottom bracket for the Altus crankset and I have to wonder whether that BB might be a little too wide for the Kona. The worn out triple was mated to a 112mm unit. The FD is also showing its age but seemed to work well with the old crankset. There are no issues with the RD.
I'm wondering if a switch to a shorter bottom bracket might make for a more usable shift on the front end.