Cadillac Repair: 1990 sedan deville runs rough, vacuum line, plastic vacuum

Question
Have the large 100 buck factory manual.  Trying to run down all the possibles listed by manual.  One is check the MAP hose on/near the throttle housing for leakage.  Can not even guess what/where MAP hose is.

Answer
If there was a fault with the MAP sensor the CHECK ENGINE light would be illuminated.

Is your engine roughness ONLY at idle speeds or can you detect a miss while cruising ?.

Look on page 8A-201-0 Figure "A" and you will see the MAP sensor. There is a rubber/plastic vacuum line attached to it. Check the vacuum line for cracks .