pulled a vacum on my 93 f-350 ,according to my guages i cant release the vacum indicating a blockage.ipulled the orfice,flushed condensor installed a new comp,the original got the black death,filled the system with oil and changed the dryer.after the failed vacum attempt i broke the system back down blowing air through the condenser and all the lines when i blew air into the evaporator 8 oz of oil came blowing out could the blockage be in the evaporator

 

I have no personal experience with "black Death", but as I recall, most guys recommend a new condenser and discharge line, because its too hard to get the junk out. The Evap and suction line can be flushed I believe. Maybe some goo moved around and clogged your orofice tube?
Sorry I can't help much, but you might go to www.aircondition.com there were a bunch of posts about black death; A lot of pro A/C techs will answer questions there.
good luck!
mike