3800 rpm bucking, ok below, ok above - all gears Options

[Axel]

1976 FI 2.0 all stock.
Put it away for the winter, now it stutters like crazy under a load at 3,800 to 4,000 rpm. It stutters and bucks so much that it won't pull itself out of the trouble range. Tachometer stays steady. If I shift to a lower or higher rpm gear, it runs great.

Checked compression, dwell, timing, valve adjustment, spark at plugs, coil resistance...All within range.

Distributor cap, rotor, condensor, and points all look good and have less than 400 miles on them from last year. I can't seem to find any vacuum leaks, but will be replacing all vacuum lines later this week. New plugs last year also...They are still gapped properly, but the 1 through 3 plugs have some dry carbon buildup that is not present on cylinder #4 plug.

Haven't yet checked fuel pressure...Can't seem to find a tap point on the rails.
Haven't changed the fuel filter yet since the last one seems to have trapped itself under the tank...Not an issue, I'll be replacing the lines with stainless from Tangerine when they arrive. Not sure how it can be fuel related since the car runs great outside of this rpm range. Seems to me that it is more likely to be electrical.

Anybody ever run into this issue? Any suggestions would be appreciated.
Axel (IMG:style_emoticons/default/wacko.gif)

[Axel]

Points look clean, dwell is at 50 degrees.
Distributor cap, rotor, points, plugs, coil, and condenser were all replaced approximately 400 miles ago. I have another full tune-up set including new wires, so I'll start replacing part by part to see if it makes any difference.