Kill me now, please.

I have narrowed it down to something in the rod caps... i just torqued them down again and got all the resistance back.

I wouldn't trust me if I were you, but if I were you I'd pop for a new set of rod bearings. Check the shells for the size (they typically get marked 010/020/030 on the backside somewhere, or -001, -002, etc) and get the same oversize version from your local (decent) auto parts store. Ensure all caps are aligned properly, use plenty of assembly lube, torque them per spec (often a good idea to use a feeler gage to take up end-play of the rod ends while torquing. Keeps the torque from deforming the new bearings) and run the piss out of it. It sucks, but there's far worse things that can happen to a bottom end.

The reason I say to replace is because if a cap was flipped and torqued, it's possible the bearing was squashed. It can crack, and delaminate or will simply be out of round. Neither is good, and since you're already there it's relatively fast and cheap. So long as it's not a track car, your rod bolts should be OK so long as they torque up.