Bike chain "skipping", but only when not continuously pedaling So I put together a bike a couple months ago. New chain, new chainrings (3 speeds), and new rear cassette (8 speeds). Used front and rear derailleurs from a bike co-op. The free wheel is old but seems to be working fine. All components are Shimano.

It had been plugging along just fine until recently. Now any time I stop pedaling, such as at a stop light or a bump, when I start again, the chain "skips" or "jumps". I'm not trying to change gears, it just feels like the chain is disengaging and then reengaging. It's infuriating and I think pretty dangerous.

When I'm pedaling continuously on a trail, no problem. When I'm standing up on my pedals going up a hill in 2 (front)/7 (rear), no problem. This info, combined with the fact that the entire drive train has to have less than 500 miles on it, and the fact that I went into another bike coop and the tech there measured my chain for wear and found that it wasn't worn makes me think this is not a worn drive train problem.

My guess is that the rear derailleur is properly keeping cable tension when I stop pedaling, which is somehow (?) causing my issue.

Any help is greatly appreciated, it's really my only form of transportation and it's getting to the point where it's unrideable.
Posting this to help others who may stumble upon this.

Took my bike into a local coop, armed with my roommate's hunch about the freehub body, and I removed it, and the guys there said that it had too much play and wasn't ratcheting correctly. Either damage to the pawls or gunk.

Put a new freehub on, and it's as good as new. The take away here for me was: if you're able to stand up on your pedals while going up hill no problem, and your chain only feels like it's skipping after the freehub disengages (coasting) and then reengages (starting pedaling again), it's probably not the chain or cassette/chainrings.

I think this is a weird problem since I had brand new gears and chain, but a very old freehub, which I doubt happens too often, but this worked for me, for what it's worth