The problem began on a long ride roughly 1 week ago.
I was riding with my headphones on and felt a slight "pull", it felt like a tad bit more than a minor crack in the roadway. I immediately felt the bike began to "drag" and my mph avg dropped 2-3mph. I can't tell for certain if the problem only happens when I stop pedaling, but I do know for certain that while I pedal it demands more effort. I removed a tire thread that peeled off of the sidewall and wedged itself between the hub and the wheel assembly.
I'm guessing that there is still some thread stuck between the hub and the wheel assembly.
Sluggish (2-3mph drop)
Pedaling the bike (inverted) the pedals continue to spin with the wheel.
Running the freewheel counter-clockwise moves the wheel itself.
I have a bad tendency of over-tightening my skewers. (Add to problem?)
2003 Specialized Hardrock, 2004 LOOK KG386i, 2005 Iron Horse Warrior Expert, 2009 Pedal Force CX1
The pedals moving with the wheel points to a bad freewheel but that won't cause any drag when pedaling. Have you tried removing the rear wheel and seeing if the axle turns smoothly? Are you sure the rim isn't rubbing on the brake pads at any point? Over-tight skewers generally just ruin the skewers. If your bearings are already tight, an extra tight skewer will make things worse though.
too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter
Odds are there's more of that thread wound around the hub behind the freewheel, binding the hub and sprockets making the freewheel less free. Get a flashlight and take a look behind the freewheel, and if you can't see clear to the hub, that's your problem.
Sometimes you can clear it with a screwdriver or ice cream stick, other times it's wound so tight that you have to remove the freewheel to unwind it.