'86 Westy

I'ved talked about this problem before and tried the suggestions from the
list. I have more info and a list of things done.  I suspect I may have
more than one thing wrong...but I don't know.  I'm quite frustrated.

This started with severe engine cutout...tach would go to 0, then back up
to RPM, causing severe bucking.  Hunted and searched and finally found
plugged fuel filter...violent bucking went away.

Only to be replaced by a gentle stutter when cruising below 3000 RPM or
lightly accelerating up to 3000 RPM, after 3000 RPM I do not notice the
stutter.  This is not noticeable on the tach.

I've tested the O2 sensor - van does same thing, plugged or unplugged.
I've removed the Temp2 plug - van runs worse with it off
Check timing - ok
Fuel filters are both new
Distributor cap looks good
Hall Sensor getting correct current
Jiggling wires does not increase or decrease problem.

Could this be the AFM giving me troubles now?   Van also runs very rich,
exhaust smells like fuel.

Thanks
Gregor