Ridiculous drop in power...

[Sandstone VR-4]

After verifying the above graph, if you determine that the trans is shifting at those numbers (R&P ratio won't matter) and you are within range, I would HIGHLY suspect the throttle pedal assembly as being faulty. Had it happen on a F-350 several years ago and it sounds very similar to what you are describing.

Thanks Dave,

I've been starting to lean towards the culprit being a potential throttle issue, as mentioned by someone above. Maybe the TPS, but I'm not sure how that could be causing the thing to throw a misfire code...

The problem sometimes gets marginally better after a battery disconnect/reconnect, but it always seems to come back to this sluggish non-response from a stop.

Very frustrating...