You can always try this for S**ts and giggles.
Inspect the MAP sensor vacuum hose connection at the throttle body and sensor, then repair as necessary.
Test the MAP sensor output voltage at the sensor connector terminal B (as marked on the sensor body) with the ignition switch ON and the engine OFF. The output voltage should be 4–5 volts.
NOTE: The voltage should drop to 0.5–1.5 volts with a hot, neutral idle speed condition.
Test engine controller terminal 5 for the same voltage as in Step 2 to verify the wire harness condition. Repair any problems, as necessary.
Test the MAP sensor supply voltage at the sensor connector terminal C with the ignition ON. The voltage should be 4.5–5.5 volts. The same voltage should be present at terminal 6 of the engine controller wire harness connector.
Repair or replace the wire harness, as necessary. If the engine controller is suspect, use Diagnostic Tester M.S.1700, or equivalent, to test engine controller function.
Test the MAP sensor ground circuit at the sensor connector terminal A and engine controller connector terminal 4. Repair the wire harness as necessary.
Test the MAP sensor ground circuit at the engine controller connector between terminal 4 and terminal 11 with an ohmmeter. If the ohmmeter indicates an open circuit, check for a defective sensor ground connection located on the right side of the cylinder block. If the ground connection is good, replace the engine controller.
NOTE: If terminal 4 has a short circuit to 12 volts, correct this condition before replacing the engine controller.