1990 Buick Park Ave.

SOURCE: intermitant stalling hard starting replaced ecm,

Hi, first thing, is your check engine light on? if it is, you can check the codes yourself, get a paper clip unfold it so you got 2 straight ends, find your dianostics port where you plug in the scanner, take the paper clip and stick one end into the one on the far right and the other to the one next to it and turn ignition key to on position, check engine should start blinking if not move the last end of paper clip you plug into the next one in port until it does( turning key off each time before you move paper clip end) do this procedure until the light starts to blink. When it blinks count the blinks, for example it will blink one time than a pause than blink twice quick which means 12 and so on. It will start out with a 12 which means the computer is ready to give stored codes. Just write down the codes and either take them to napa, or auto zone, or to a shop you know, and they can tell you what they mean. On a car that old it could be almost anything, parts wear out, but right now what stands out to me by your description i would check the cadalitic converter it might be plugged. Take some advise get someone that knows something about cars or at least works on them on a regulator bases. That way your not playing a gessing game.