Bogged down While In Gear And Sputtered During Acceleration

Hello All,

Yesterday while driving I lost 50% of power and experienced a sputtered acceleration-giving it gas from stop it lurches forward then quickly sputtered and "coughed" but still moves. Everything has been running fine for 8 months and this is a daily driver.

When I put it in gear (a904) the manifold vacuum drops from 16 to about 7 and feels bogged down. While in park or neutral the engine idles and revs great.

To make sure it wasn't a carb (Eddy 1406) problem I pulled it and ran it through an ultrasonic cleaner, rebuilt and replaced the gaskets. Same thing. Idles and revs great but in gear it falls on it's face.

I also:
Disconnected the vacuum advance
adjusted the kick-down linkage
replaced the tranny filter and fluid
swapped plugs
Checked plug wires
tested voltage at regulator and ballast resistor.
Re-checked timing
Re-Checked valve lash
Did a propane bottle and carb cleaner vacuum leak test on the intake.

I am pretty sure I have eliminated this being a motor problem and now thinking converter or tranny. 8 months ago my 273 got a refreshed set of ported heads, cam, lifters, etc., increasing the compression HP etc. but nothing too racy, maybe an est. 250ish HP 273 that is driven daily and not hot-rodded. Until yesterday it has been running like a champ but I have noticed a slight harder "kick" when putting it into R or D over the last few weeks.

Any insight or advice is greatly appreciated.


Specs:
273, .473 lift cam 262 duration, eddy performer intake and 1406 carb, Mopar electronic Ignition and distributor, A904, 7 1/4 rear.