So it sounds like this one is a bear. Is there any way you can see replacing it without removing the intake plenum? I have done that before to replace the spark plugs, but I don't want to have to remove all of that mess again if I don't have to.
You can do it without removing plenum. I did it.
First, get 1/2 extensions. If you use 3/8, they WILL break. Mine did. You need few long ones, needs to be at least 3 feet. (I think I used two 12 inches and one 6 inch one). And get a breaker bar. Forget torque wrenches.
Remove driver wheel, put car on jack stand. Put wheel underneath. ONLY Remove one wheel.
SAFETY First - put 2 jack stands instead of only one. You don't want to die. I used 3 jack stands (i have 4 stands)
Remove wheel well plastic dirt panels.
Look through around rear side to see rear mount side bolt. (forgot what size). You can see the bolt from the wheel well.
Don't use impact, the extensions will bounce around and don't do much. I tried as well. You have to use manual force. The bolts are really tight.
Break the side bolt with the extension and breaker bar through the wheel well. (Put one end on another jack stand so you are putting on a straight horizontal level force). -- Some people were able to break side bolt from bottom with a wrench. You can try that as well.
Open hood as much as you can, remove it if you need to. I did it without removing.
Go up on top of the engine (gingerly) - don't break anything with your foot. You can put your knee on the plenum and my foot on the air filter box. be careful with the MAF sensor connection sticking out.
you can reach the two vertical bolts from behind plenum with extension and socket. Break them. The reason is, you do not have room to maneuver the breaker bar from the bottom. They are really tight so you really need a breaker bar to break the bolts.
Put jack under engine - with a flat wood on either oil pan or the transmission hump and raise it like 1 inch.
Then, go underneath and use socket and wrench to remove the two bolts (I think nuts are fixed in there). And remove the side bolt and nut.
You will have to wiggle the mount out from bottom.
Install is reverse.
It took me about 3 hours.
It takes time because unless you have a lift, no room for even a small cordless impact wrench underneath.
Remember, the bolts are in really tight. But, forget the torque wrench. Just put them on tight as you can. They are not going anywhere.
Key is, good 1/2 inch breaker bar, several 1/2 inch extensions, 6 point 1/2 inch sockets, 1/2 inch wrench, 3/8 sockets and wrench, impact 1/2 inch U-joint (they don't flop around as much). You will need that U-joint.
Jack and several jack stands are given.
I think you can spray penetrating oil before to help with loosening bolts.