Alrighty, First off this is for a 2.4L G6, also it is a 2006 (If yours differs my bad, just a simple guide)
Good ol' Check engine light came on, so I had it ran, read MAP Sensor. Replaced it and bam! Luckily for you I recorded the process with pictures! Now I'm going to use those pics to make a guide as I could not find one for myself to use.
Vice grips (Any plier would work, needle nose, whatever, even channel locks)
5/16 Socket and Rachet (Flat head screw driver would suffice)
And I used a 5/16 socket bit with a screwdriver
All you really need is a Pair of pliers and a flat head to do this job, so if your lacking in tools, don't fret.
Be sure to unhook that Hot cable from the battery when dealing with sensors
Used a 5/16 socket/Rachet to undo the terminal (Vice grips work but careful! It can damage the threads o.o)
I have marked three (3) areas that must be undone to be able to remove the plastic housing that covers the throttle body.
(A) Pinch clamp (Use pliers or vice grips and slide it up off of the plastic lip)
(B) The item needing to be undone here is a large clamp, use either a flat head screw driver and/or a screwdriver with a socket bit. Note: The clamp is not shown as it is BENEATH the plastic housing, to access it you need to look under it. Remove the oil dip stick (gets in the way, at least for me) and you should be able to see the clamp from the right portion of the engine.
(C) is out of screen, but it is an identical clamp that attacks the plastic housing to the Air filter box, undo that clamp and remove that hose as well and now you should be able to remove the plastic housing to reach the next step.
Pic of item (C) the air filter box clamp
After the housing is removed you should bere here: Your nearly complete! Whoo! pat yourself on the back because the hardest part is over!