1986 Comanche Idles Fine/Runs Rough Under Load

[slimpartywagon]

Working on a friends 1986 MJ with a 2.8L v-6 auto transmission 4x4.  I have been beating my head on the wall over this one.  The truck idles fine, and even accelerates and decelerates normal when in park or neutral, but when put into drive it dies when the engine is cold.  If you wait for the engine to warm up the engine will run in drive, but has no acceleration, back fires several times while accelerating from stop to about 15 mph.  from 15 mph to 55 mph there is no power, and feels like the transmission shifts way too soon, and the transmission won't kick down when the gas pedal is pushed to the floor.  Hard braking causes the engine to die. 

 

What I have done this far

 

Rebuilt the carburator because original symptoms showed signs of a bad accelerator pump (rebuild fixed that issue)

Replaced a couple of broken vacuum lines going to the distributor and EGR valve,

Replaced carb to intake manifold gasket

New Plugs, Cap, Rotor, and wires

Checked timing

 

The symptoms remind me of a vacuum leak, but spraying the vacuum lines, motors, and diaphragms with ether doesn't change the way the engine idles. What could I be missing.