When i drive and accelerate sometimes even when not accelerating the car stops for a second and then jumps, It feels like the brakes lock up for a second and then the car jumps and if i accelerate when this happens it happens more frequent but if i let off the gas it and accelerate slow it drives ok.

I got my transmission replaced because of this and the problem still presist, just fixed a leak in transmission as well, What can this problem be?

I have no better way to explain this, Other then I cant drive on freeways because at high speeds it happens more frequent the car complete jerks and brakes, one time the car completely shut itself off while driving and all my warning lights came on,then after sitting parked for a few minutes it drove fine.

Im out of funds and ideas, got the new tranny or rebuilt, replaced gasket, new car battery, new coolant tank.

please help