What cause below normal MAP sensor readings? on 2001 Jeep Cherokee

130,000 miles, 4.0L motor. Engine runs good. Have checked MAP operations, good. TPS-good, O/2 sensor, all four are new and good. IAT-good. Coolant temp senor good. No DTC. Using to much gas. Could their be a restriction in the exhaust sytem causing this????????????

Asked by for the 2001 Jeep Cherokee