> On my 86 Vanagon diesel(ok its really a Jetta) which I just bought I noticed
> recently that it "stumbles"(misses) under acceleration.  Any thoughts from
> you diesel folks out there?
> P.S.  Thermostat seems to be stuck open, little heat and the needle doesn't
> move off cold ( I know the guage does work after taking the car over the
> mountains).
> 
Does pulling the cold start out make a difference in the stumbling? 
If so, have the pump timing checked. Does it run rough at idle, or 
certain rpms when not under load? If so, try running the engine at 
this speed to induce the stumbling. Then loosen the injector fuel 
lines one at a time (smaller ~14mm nut on top of injector) just until fuel starts 
to seep out. If the engine stumbles even more, or stalls, then 
continue to the next one. If you can loosen a fuel line (don't take 
it off! High pressure) to the point of fuel seepage, and NOT affect 
the engine running noticeably, then this injector/cylinder is not 
functioning.
Also, replace that thermostat asap - running too cool is not good the 
diesels, although they should not stumble badly if everything else is 
ok.

Shawn & Janis Wright
'88 Westy (336k) '85 Jetta TD (361k)
VWnut@smus.bc.ca (swright@smus.bc.ca)
http://www.islandnet.com/~swright/vw.html