Duster Engine Swap

225 /6 engines, and 904 transmissions are proven to be awesome powertrains.

Yours needs some immediate attention, NOT a owner who is ready to quit and drop in some other manufacturers lower quality powertrain.

Check the oil on your engine.
Pull out the (6) spark plugs. Inspect them/replace them.
Remove and Install a New Fuel Filter
Replace the Distributor Cap and Rotor.
MAYBE Replace the wore out fuel pump.

AND PUT SOME MERCON DEXRON III Fluid in that transmission! The damage is probably already done.

Maybe pull the driveshaft and replace that leaky tail seal!!

BLASPHEMY!! I tell you!