Which country is this car from? If it has the 1.5L 4G15 in it, that is a different engine control system than the 2.0 sold in the US.
The base engine is the same as sold in the earlier 2002 Mirage, but the US versions have to meet OBDII specs while the other countries do not so they use a slightly different control system depending on the country they are sold in. There still should be the same three wires (five volt, ground, signal) for the MAP but the five volts feeds both the MAP and the IAT.
I would expect the readings to drop when you unplug the MAP as it loses the primary control signal and switches to substitute numbers to make it run. With the MAP in circuit it is pulling fuel out. What did the plugs look like when you pulled them out? If this car is burning a bit of oil the O2 would show it was running richer than it should and cut back on fuel. It would also do that if the fuel pressure was higher than spec. Or if it has a misfire in a cylinder.
What test equipment do you have or can you get a hold of? If you can get a scope you could look at the ignition waveform and see if the burn time in the cylinders match. Even those old Sun monster analyzer scopes could show that.
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Wednesday, April 18th, 2018 AT 1:57 PM