I saw this thread, after having some of the same issues as everyone else. The drivers side went great for me, knuckle and two sub frame bolts came loose with no problem.

The passengers side is giving me no end of trouble, but I think I have a plan.

Today I tried to heat the heads of the bolts with the oxyacetylene to no avail, I had them glowing red hot, and considering how close the front mounting bolt is to the oil pan and filter it was pretty ballsy in the first place. After no movement and breaking the nut inside the subframe (we tried every trick in the book) I think I have a plan.

For the front bolt:
I am going to cut a slot in the sub frame where I think the nut is, probably an inch wide and two to three inches long. Then slide the sawmill and cut the nut from the mounting bolt. After this I should be able to pull the mounting bolt free with a hammer and punch. Then I will purchase a new nut and bolt and using my original slot re-mount the new control arm. I am still debating leaving my slot and rounding the corners to reduce the possibility of cracking, or welding a filler piece in (I am pretty confident in my TIG welding, but once again being so close to the oil pan and filter makes me nervous).

We have debated so many options here, started off thinking we might drop the entire subframe and do this on the bench.

I am thinking that if my plan works you should be able to comfortably make this fix in two to three hours, should I run into no issues.

If I decide after this clusterf*** that I want to keep my Lancer, I will probably get back under there and weld a plate over the portion I cut out on the subframe, to take some of the strain away from my access hole I will cut.

Let me know if you have questions and I will most definitely try to document this as I go through the pain.

For that vertical/rear mounting bolt:
I am going to start by removing the interior carpet, hopefully once I remove the front bolt, my good friend Mr. Sledge Hammer and I can get the old control arm and bushing turning around the bolt, if not I will cut a similar slot and try the same thing.

I hope Mitsubishi redesigned this and never sells this type of control arm mount again, what a nightmare.

Thank god it has been above 10degreesC in Canada this week...