say i have the car on, i test the pistons by pulling the spark plub wire on each piston. if u stand in front of the car, say u have wire 1..2..3..4. well, when i pull wire 1, 3, 4, the rpms go down, but when i pull wire # 3 the motor chokes and shuts off. y.......is this ?

 

that means your number 3 is losing compression i think! or number 3 is your problem somewhere