83 1.9L wbx Canadian

Took the van out today for a run of about 5 km to the brunch spot. All
OK. Came out afterwards and engine cooled to warm temp (needle full
right) Starts up fine on second attempt (normal for this engine) and I
drive off. Stuck at a stop light for a couple of min. Enter traffic
stream OK. Two blocks and another red light. sit and idle OK start off
and I have no power. Stall it. Restarts easy. still no power like it's
not getting any gas or air. won't rev, back fires. runs like this for a
minute, then finally responds to my throttle manipulations. and I drive
home in second gear to keep the revs up. It runs strongly at higher
revs but will not come off idle.
Turn into my alley, letting the revs drop and it goes back into no
power, won't rev and backfires then stalls. Wont start.  Check for
loose wires  to no avail. reseat temp 2 connector to no avail. Try to
start with throttle wide open as in a flooded engine, Stumbles and
starts and i drive the 1/2 block home till it stalls in the driveway.
Won't restart. Allow to cool for 1/2 hour. restarts easy. rev it a few
times and it starts to stumble then stalls off idle.

ARRGGHH!!!
Any clues where to start looking??
TIA