My '87 764ti with 141kmi has a very high vacuum while driving around. While coasting, foot off the gas, my aftermarket gauge reads about 20inHG while the in car gauge (stock) reads almost off the scale! Once it even hit the end of the travel limit! What could be causing this? I also have high crankcase pressure (don't pass the jiggle test and have pressurized air coming out of the CV return line when i take it off). I also think I have a clogged cat because I ran the car for a few months with a bad O2 sensor and a few leaky hoses. (My fault! I know its bad!) Could I get the specs for what should happen when, etc, what pressure/vacuum I should have when I do.....
Thanks! Your help is so greatly appreciated.