Nissan quest 2000 engine problem

My Nissan quest 2000, 145000 miles on it. Could’nt get it started at first - changed fuel filter, fuel pump, spark plugs - got it checked on computer - Crank shaft position sensor and knock sensor needed to be replaced. Changed the crank shaft sensor but still showing the same problem on the computer. Later it started but when give gas the engine stalls and shuts off. The engine sound is not normal -a gasping sound is heard every few seconds. Please advise.