D-Jet hell

[Peter Lindberg]

The D-Jet system in my '71 Volvo has been very reliable and (relatively)
decent running, but the engine is very lacking in low rpm power.  This
engine (B20E) is not known for being particularly 'torquey' to begin
with, but I'm sure something's not quite right.

I've done the basic resistance test with all of the electronic
components.  I recently replaced the injector seals, and gave a complete
ignition tune-up and valve adjustment.  When I was replacing the
injector seals, I examined the spray patterns of the injectors, but did
not do a flow test.  

I know the spray quality affects low end power, because the injectors
are triggered in pairs.  Are there any other possibilities besides the
injectors?  What can I do, other than buying a new set of injectors
($250) or having them 'serviced' -- which I'm not sure I trust --
($120).

Is there any DIY way of renewing the injectors?  I've tried several
brands of the pour-in-the-gas-tank cleaners, none of them seemed to do
anything.  I thought maybe forcing solvent backward through the injector
with compressed air might do something. . . 

any tips, ideas, suggestions?

By the way, another D-jet question:  Can the manifold vaccume sensor
sense manifold pressure as well as vaccume, or could it be modified to
do so?

Peter Lindberg