Black gooey stuff is expensive insulation/tar tape. Only comes in huge rolls, I recall. Its very important you retape the TEV with it as it could freeze up and malfunction. Also, dont bother testing a TEV- if you went to the huge project of removing the evaporator/removing dash, get rid of it. get new. Theyre cheap.
Also, you should not have to run car for 30 or so minutes to test ac- more important is to rev up rpm's to 1500-2000 to test. Take a spin around the block in it- that will do much for the system.
87 spider veloce