The chain on my mid-90's era mountain bike recently broke. It's the OEM SRAM chain on a Shimano 8-speed drivetrain. I replaced it with a KMC 8.99 8-speed chain, but now I'm seeing a weird problem. If I pedal backwards, the chain downshifts to smaller cogs in the rear. Pedal forward and it jumps back up. I've made numerous adjustments but still happens. This doesn't happen with all the cogs. Also seems a little noisier than with the old chain.

Do I need to stick with an SRAM or Shimano chain?

Thanks.