1992 Nissan Maxima can't start

Engine problem
1992 Nissan Maxima V6 Front Wheel Drive Automatic 190000 miles

Dear Helper,

i just water washed my car and changed it's two valve cover gaskets to stop oil leaking. After that, the car can't start without press the accelerator. Even under such condition, the engine runs abnormal, just like one of the six cys doesn't work. I changed new distributor wire. The timing is correct, the distributor cap and roter are dry (no water got in). The car runs well before I did the work.

can you help me?