What's an easy to use filler for old screws holes and something that will fix the splits in my deck joists?

I'm replacing some of the 2x6's that have warped and I'd like to repair the joists that have splits and stripped out screw holes from the 2x6s warping. I need something that will allow the screws to to driven through the same spot or very close.

I thought about using epoxy but it might be too tough when it's cured without pre-drilling all the holes. Mixing wood glue and sawdust would work well but I'd rather buy a ready made product

Ideas?