1994 Nissan Maxima Timing belt repaired but wont run still

My timing belt broke. I replaced it, I got the timing marks on the belt, cam sprockets, crank sprockets, alined with the markings on the rear timing cover for the top two and the mark on the oil pump for the crank shaft. I have to hold the gas to the floor to get it to start and keek it above 1000 rpm to keep it running. It runs rough and dies when I let off the gas at about 800 rpm. What did i do wrong or what am i missing. the car was running ok untill the belt broke. Please help!