I have had this problem for a while now but yesterday it happened as well and that time it was very bad.
I was listening to music in the car for 40 minutes, (the audio system turns of in 10-15 mins) so i had to put the switch on on to off a couple of times. When I turned the car on the RPM was weak in between 400-500. I thought maybe something wrong with the battery or something of that sort. I let it idle for like 20 seconds and it stabilized over 500. Now my rpm is usually at 680 and the car is running okay at those times. When the rpm was at 500 I revved it up to 3k and let my foot of the gas until it got to 1k and i suddenly took it off the gas and the rpm dove down to 200 and almost stalled. Another thing is that when I put the car from park to reverse the rpm drops significantly as well. This is always an issue(it drops to 500 from 680 rpm at normal times and idk why) but during this time it drops to 200 as well. When I was driving normally I noticed that when taking off my foot from the gas the car was being choked even if driving at 40 mph

This is very reminicant of that one time where I Was changing the pcv valve and broke the upper plastic lining so I had to drive the car to auto store with the lining off and I had similar symptoms.
So do I have a vaccum leak? If so why dont I have symptoms all the time?
Battery/alternator? IAC valve? fuel pump? or should i just get a new car instead....
Also I rented a fuel pump test tool so Ill post the pressure readings as well.

 

When is the last time spark plugs and wires changed? Has the throttle body and maf sensor been cleaned lately? Mine idles around 530, 550. So I wouldn't think 500 would be too low unless it's kinda sputtering and dropping rpms.

 

Those were changed 1k miles ago, all the basics have been taken care of. only sputters and drops when its shifted to reverse/neutral or while driving whenever I let off the foot off the gas pedal

 

Have you done the fuel pressure readings yet? I'm no expert but maybe some live data of the fuel trim would be helpful, see if it's running rich or lean when the problem occurs.

 

I did that and it was at 59 but at that time the car was running fine and it has ever since I made this post. I have a blue driver scanner capable of showing me mode 6 data and the fuel trim readings. What should I be looking for exactly? I will scan it next time this thing happens