is300mia

So i have a 1999 is200. I recently changed the engine from a 1jz to a stock 2J injector. ive been running the car for a week-2 weeks and it was fine, a small misfire but i changed the spark plugs and that fixed it. But recently the car started cutting off as i drive. It was initially in high revs, the rev gauge drops on the dash when it cuts and the engine light turns off. Now its happening alot more in the low revs and seems to only happen when the car is warmed up. Its undrivable. The car jolts hard when it cuts and the car basically dies for a second.

Does anyone have any idea as to what this could be?!!