I was constantly PTing in 169-175 range and don't think I got anywhere near that. It could be a first time test taker issue but I found the test way harder than the 80s which people say are the difficult test sections

The cause and effect in AC C isn't talking about whether or not pollution is eliminating many of the species every year. The cause and effect is between 1) biologists learning that many more species of amphibians exist than had previously known; and 2) the claim that pollution is eliminating many of these species every year.

The argument gives one premise (more species exist) and extrapolates from that premise that because of it -- the claim that pollution is eliminating many of these species every year is incorrect.

AC C is wrong because it's descriptively inaccurate. The confusion isn't between whether or not this newfound knowledge of additional species is the cause that undermines the claim that pollution is eliminating many of these species every year.

The flaw is conflating one thing (changes in our knowledge) with changes in the actual species themselves. As you stated, just because we discovered more species than previously thought doesn't mean these species AREN'T still getting wiped out every year. That is what AC E is telling us.

I'm facing this same issue and am averaging around -0/1/2 on untimed LR vs 2/3/4 on timed LR. As for RC, I recommend just timing it in general -- but you can split it up timing and breaking for each specific passage vs drilling the complete RC section timed.

For me, my issues are simply a matter of reading too quickly or failing to process the information worrying in the back of my mind that if I should continue thinking or skip ahead to the next question (because of possible lack of time).

As the aforementioned poster said, learning when to diagram and when you can make a specific inference/choice in your head is a big time saver. Additionally, it helped me to set a timer on my "untimed practice test" and just do them with the implicit knowledge that I shouldn't spend too long (3-5mins) per question and treat it like a quasi-timed drill helped my speed.

The fact that you are BR-ing in the mid-high 170s but practice testing in your range isn't a consequence of a fundamental lack of understanding of the material -- it's more of the way of how you mentally process solving each problem within the time constraints of a test vs without the constraints. I think training your mind to remove the distinction of timed vs untimed problem solving-- primarily through quasi-timing would help in some sense.