Chain sometimes jumps. New parts Can't seem to get to the bottom of this. I have an 1997 Marin Eldridge Grade. I use it mostly for touring. The chain jumps or skips. It doesn't Jump down to a smaller sprocket. What the chain does seems like it could be several things. 
1.It could be riding up on the sprockets 
2. It could be riding up on a chainring
3. It could be a pawl skipping.
The problem is, pretty much everything is new. 
New LX chainrings,New chain Probably a Whipperman Connex 808, 8 sprocket XT cassette, and a new freehub.
It doesn't skip/jump all the time and i think it is more inclined to do it at moderate load. It seems to be getting worse.
I've been a cyclist for 43 years and can sort most things out myself but this is doing my head in.

Chain is not jumping up and or down sprockets so not changing gear. It is riding up on teeth of sprockets or chain rings. I have already stated that chain is new.
Shifter and Derailleur are Shimano XT.
No stiff links in chain.
Even though the chain is new, you could have a stiff link.  I assume you cut the new chain to get the correct length.  If so I'd start there to make sure you didn't mess up the first remaining link.  Then I'd manually check each link for a stiff one.  If you find a stiff link, you can sometimes loosen it up by bending it a bit side to side.  That is at 90 degrees to plane of the pivot.