Originally Posted by 60wag
If the cat is restricted, the manifold vacuum should drop to near zero well before wide open throttle and make the truck noticeably slower than normal.
An issue that could show up on 60s (not sure about 80s) is a collapsing lower rad hose that restricts flow. A new lower hose or adding the internal spring to it solved that issue.
I read about the lower rad hose, is there a way to check it or do i just have to replace it?