94 chev pu 5.7 liter code 33

tested map sensor working ok found 5 volt referance on referance wire,ground on ground wire ,and 4.3 volts on map return wire, light green wire , with map sensor disconnected still has 4.3 volts comming from pcm side traced wire to ecm . no shorts to power the map signal wire . i even cut wire close to pcm and still has 4.3 volys on pcm side of wire , tests said bad pcm installed another one and same problem any help could it be a bad pcm with the same problem ,map signal wire shouldnt have power from it with map disconnected?

Zigzag, I looked up code 33 in my Haynes Emission book it says map sensor or circuit low vacuum, Maf sensor or circuit voltage out of range (probably high).