Suspension wobble plus a few other questions

[XakkGrill]

So I'm brand new to the 240 world. I guess this is kinda my intro as well. Bought my first s13. I mostly work on my MR2 Turbo, so going to an FR is a little strange. Im looking for some guidance.

I got this chassis for cheap and one of the main issues that I have is a crazy wobble over bumps. The car rocks side to side and back and forth over noticeable bumps in the road. The car is on some cheap coils(Function and Form type 2's I believe?) welded diff and solid rear subframe bushings. I bought the car slammed on its ass, collars taken out, whole nine yards. I reset the preload(10mm), raised the car, adjusted the damping from full hard to manageable, and I still have this death wobble.

Now, the wobble is not in the steering wheel, it is the entire car; as if it were a chair with a short leg. I do get steering wheel shake around 45mph, but the outer tie rods and tires have seen better days(along with most of the suspension parts). I would like to not go around replacing all of the bushings and it not fix the problem.

The previous owner said it might be because the car has no front swaybar, I find that hard to believe, but Im new to this car.



Completely unrelated questions:
My coolant temp gauge doesn't work, Im assuming it is the sensor. If someone knows the part number for the sensor that would be awesome.

Also its has a KA24DE, with an s14 intake manifold. Supposedly has a s14 IACV which gives me trouble in the morning at cold start. Can I throw a s13 IACV on it and fix that issue?

Thanks.