89 that runs like crap

my g/f has an 89 chev cavalier that had a 3.1 put in it. it fires up great and runs fine at first. after that it sputters and quits on her. any ideas? i'm just about to start work on it and i'm lost.

my g/f has an 89 chev cavalier that had a 3.1 put in it. it fires up great and runs fine at first. after that it sputters and quits on her. any ideas? i'm just about to start work on it and i'm lost.
I'd change the fuel filter,plugs,if it still did it i'd pull codes to give me a general idea of wich way to go,on my 88 you can pull codes with a paperclip

I'd change the fuel filter,plugs,if it still did it i'd pull codes to give me a general idea of wich way to go,on my 88 you can pull codes with a paperclip
how do you pull the codes off of it??
would injectors make it do that too?

Yea I think injectors could do that maybe you could run a bottle of injector cleaner thru it,it helped my S-10 ,it would start up and not die like your car but it would idle rougher than hell.

Go to the local autozone and ask them to use an OBD 1 on your car...

Perhaps the people who put in the 3.1 didnt put in the 3.1 fuel pump. If it still has the 4cyl pump in the fuel tank, you are lookinag at about 30psi short of what you need...

hey guys thanx for the help. two of the plugs were misfiring and the others were gapped toobig. 6 new plugs and now she goes. next task is the heater core feed line. i hate starting out in a relationship. lol. i'm always expected to fix their car. L8r dayZ