computer codes help

87 z28 305 carb.  check engine light is on.  gives me a code that shows a bad "differential pressure sensor".  i checked my heynes manual and it shows no such sensor.  where is it and what does it do? thanks

Its a map sensor

34, says its leaking or restricted vacuum hoses'poor electrical connection, open or short in circuit; defective map sensor;defective ecm
 

is it a bad connection to the map sensor of faulty.  how do you check it
 

try changing the map sensor, shouldnt be too expensive. if the light goes off, your set. and you have a new map sensor. 

Check your vacuum hose. They will rot and split. You will also have to disconect the battery for about 20 seconds to erase the code from the memory.