Hi.! Thanks so much for that link to the forementioned post and solution. I carefully looked at all of the diagrams and think I have it solved now!
Here are some other KEY things I discovered today while fixing this issue:
1. Replace ALL rubber vacuum hoses under the hood. There are several that directly supply the main vacuum plug on that programmer connection. Start with the ac vauum tank resevior that is located under your battery tray and in front of the inner fender well on the pass side. There is a single vacuum connection there that starts a vacuum line that is run through a black split loom and continues to the Y-conection located under your fuse panel cover. I replaced that ENTIRE LINE. Even the black plastic tubing was fragile and split in several areas. I also had to replace the vacuum hose that connects to that Y-connector under the fuse panel cover since it had a crack in it. NOW, after that, I knew for sure that was getting a full 21- inches of vacuum with my tester gauge, when I placed it into the main vacuum source hose coming through the firewall which supplies the programmer. That was the solution for my car! Now it works like it should.
ANOTHER TIP for making that programmer main vacuum plug slide back onto the programmer easily is to lightly coat the outsides of each nipple with white grease or even vaseline. It works like a charm--as long as you are very careful not to get any into the holes. Not that simple
Hope this helps other people out as much as it helped me.
FLorida is way too hot to go without air conditioning... year round...