1992 Buick Century misfiring and cutoff

Engine Performance problem
1992 Buick Century 6 cyl Front Wheel Drive Automatic

my car wont stay started.I have to hold down the gas and hurry up and change gears to go or it will cut off. It also does this at stoplights if I dont put it in park and gun the engine. People tell me I need a tune up but I think its the pcv but I dont know where it is or how to fix it.