mysterious bogging down

["Matt Harger" <MJHarger@msn.com>]

Last friday I sent a message about my '86 Quattro 4000 (with '87 engine) 
having troubles "bogging down" after a few minutes of driving.  Someone 
suggested to me that it was the injector seals.  But wouldn't it have the 
problem all the time then?  (I don't know much about cars).  It only does it 
about 65% of the time, and it seems to go away faster if I pump the 
accelerator.  Also, if you turn the car off, and then on again, you can rev 
the engine just fine, but then it just bogs down again.  It doesn't matter 
whether the car is warm or not, or whether the weather is cold or not.  Just, 
within a few minutes of starting the car, in any gear, I get no power.  The 
rpm's drop as well.  I think it's getting worse, it's VERY frustrating, and I 
don't have tons of $ to fix this, so I'd welcome any/all suggestions!  
Thanks!!    PS Are injector seals expensive to replace???  :)