Not accelerating properly/shaking

Hi, I have a recent issue with my car not accelerating as it should, especially going up any inclines. It also starts to shake when I do try to push it to accelerate. This is much worse the hotter then engine gets. If I am on a flat plane, it will accelerate slowly but, but it is hard to get it up to even forty mph on incline. It is automatic but it feels like when it needs to auto shift to accelerate past thirty five mph, it will not unless I let off the gas and try again. Then it shakes pretty bad and the check engine light flashes until I get on a flat plane again or stop giving it gas. I checked the transmission fluid, it was a little low, after adding more, the problem was not quite as bad, but after driving it running errands, it came right back. My brake light indicator is on. is it possible the e-brake is stuck in place? The light goes on and off somewhat randomly over the last month or two.