89 p.a. dies whenever it feels like it

hey all, I'm new here and am having some problems with my 89 buick park ave.
this car will idle fine, run for a while and then act like its not getting enough gas. It will act like it wants to die but as long as i am still giving it gas its ok. Sometimes just going short distance it won't give me any trouble. oh yeah and I recently had a new fuel pump and fuel filter installed. Also only one error code ever comes up and that is GDM something or other..... Pleas help

Have you checked the coil packs? They tend to die after they heat up when they start to go bad.

Could also be a poorly grounded or bad ignition control module.