I have just purchased a 1986 Monte Carlo and it has the 4.3L fuel injection motor...the car WILL start but NOT stay running, it does not have the original air cleaner and i assume since its fuel injection this is a huge factor but i need help with this because the motor is getting fuel the plugs were cleaned up and like i said itll start but not stay running any and all information is welcomed and appreciated

 

Welcome to the forum!! Congrats on the Monte!!!
Did you clean the plugs or replace them??
I would first start off with new plugs and wires.