some things not yet mentioned, but worth considering in my not all that humble opinion...
You mention "when it climbs up the apron, it bogs down like it is flooded" does it also bog under lifting a load, or only in gear (bad torque converter/ cracked stator if related to under traction/drive load, and not under any other loading).
also it is normal if the diaphragm can not move (like when you cover the vent/atmospheric side of the regulator) for the unit to die off, since the diaphragm needs to be able to flex to allow gas flow.
also, if this is the Peugeot engine, the way they are built often causes moisture to build up in the holes for the spark plugs, causing intermittent rough running, particularly if the truck gets washed.