Car shuts off when doing donuts

I have upgraded this car. Suspension, brakes, wheels, struts, and everything else underneath the car. I have had some issues recently with it though. I have been experiencing some bad acceleration and extremely horrible gas mileage. My car has trouble starting sometimes, but other than that it runs great. But if I go do a u turn quick or turn a corner quickly my car drops rpms and sometimes will completely shut off (engine only, check engine light, airbag, battery, oil lights all come on as if I just have the battery on. I pull over and start it and it's right back up and sometimes traffic is coming, so I will accelerate out quickly and nothing! Do you think maybe it has something to do with my transmission? When the car has trouble starting the RPMs needle goes to 1 then slowly drops halfway then jumps to one and back down then to one then completely down like its off. (Picture it is jumping from 500 RPMs-1k then back down.) Then will shut off and has trouble starting up. I have only had this issue when the gas is at a certain level. It is just a gallon or so bellow the last quarter of gas. I took it in for some other opinions and was told the coolant sensor was broken and maybe that could be it. I fixed that myself and no codes pop up anymore. Still had the issue. I thought it could be the camshaft sensor (even though I had no error codes for it or a check engine light) I decided to replace it and at first seemed great but the problems came right back. Gas mileage is a bit better it seems, but the poor acceleration is definitely there still with the car stalling during a you turn. The fuel filter and other filters all were good. No codes. Fuel injection was good too. Battery at 79% alternator and starter both passed tests. Car also got a smog recently which it passed. There is a drive belt chirping sound from time to time and gets faster and a tiny bit louder if I rev the engine or if driving accelerate. I would love to hear back from you.