First let's start with that SC issue. SC is evolving to be less idiom based and more reasoning based. Many of the questions in the OG, if I have it right, are from before this evolution. So it could be that the style was different enough to make the ones on the test seem harder to you.
Beyond that, what you describe is pretty surprising, in that the discrepancy between your practice scores and actual score is rather wide. 50 points would be one thing. 130 is another.
I don't think that what you said about the foundations really makes sense. I mean you need to understand the concepts and how to take the test in order to score high on a GMAT Prep test as much as you do on the actual test. I guess it's possible that you just got hit with just the wrong questions on the actual test, but enough to drop your score that much?
So there's a good chance that something else was going on.
When you took the practice tests, did you seek to duplicate the experience of the real test by not taking extra breaks and by doing all four sections?
Had you seen some of the questions on the GMAT Prep tests before, on GMAT Club or somewhere else?
Did you get enough sleep the night before the actual test? Did you make sure that you were not hungry or worn out? Was there a long trip to the test center?
Were you super nervous?
In general, was there about your taking the actual test something that was significantly different from how things were when you were taking practice tests?
Anything like that could explain much of the difference in scores.
So your next move could be to analyze the situation and see if anything that I mentioned could have affected your performance.
Then maybe you could go to Veritas
or Manhattan Prep and take one of their free practice tests to see what happens. Their tests are fairly accurate, though the Manhattan tests tend to score a little low. See what score you get, by taking the test in a realistic way, all four sections, etc., and that score could give you a good sense of what you are up against.
You could also use the test analysis provided with those tests to get a sense of exactly what you could work on.
In any case, it seems apparent that you should increase your SC skills. Also, maybe there are some quant areas that you could be stronger in in order to be sure that you won't make lots of easily avoidable errors.
So there's a plan.