My van idles fine, but the minute power is added the engine accelerates monentarily,
then drops off.  For instance the tach indicates an idle of approximately 1000 rpm.
when gas is added it will go to 2000 rpm, then drop off to 0 rpm and continue
hunting.   Impossible to drive.  Any assistance is welcome.

Originally started when van ran out of fuel.  When I poured in 5 gallons, the trouble
started.

Fred