My car stalls out has loss of power when stopping runs a little rough and it takes a long time to fill the gas tank like it shuts the pump off like its full when its not.

SOURCE: 98 buick centry 3.1 6 cyc one owner family owned

Unfortunately, you've got serious problems. The GM 3.1 and 3.4 engines have a nasty habit of breaking camshafts. For some reason, which I have yet to determine, the cam bearings seize on the cam and the camshaft ends up breaking in half. The engine will continue to run, albeit very poorly since all the cylinders are not working because the rear half of the camshaft, which runs the oil pump, is not spinning.

SOURCE: 1990 Buick Century 3.3L Check Engine Light comes on, stalls.

Need to check for fault codes. Possibly a faulty sensor causing the fuel system to run rich or lean.

SOURCE: 1991 buick regal starting and running problem

Sounds like your car is overheating. If you have a temp gauge it should show that. If you just have an idiot light, by the time it comes on it's already too hot to operate. AFTER the car is cooled down, open the radiator cap to see how much coolant has been lost. Chances are there is alot missing. Add WATER (no sense in adding coolant if it's going to leak out) and idle the car at home. Look underneath as it warms up to find where the leak is.

SOURCE: Stalling and not starting 89 buick century

First thing, is your chk. engine light on? if it is, you can chk. the codes yourself, get a paper clip unfold it so you got 2 strate ends, find your dianostics port where you plug in the sccanner, 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, chk. engine should start blinking if not move the last end of paper clip you pluged in to 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 paus than blink twice quick witch means 12 and so on. It will start out with a 12 witch 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 discription i would chk. the cadalitic converter it might be pluged. 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.

SOURCE: 97 buick lesabre 3.8 Idles rough and stalls out.

Fuel injectors go bad on these engines, you can find re manned ones for 30 bucks. If you have an engine light on get that read. Change your coil/wires/plugs also. Is the lower intake manifold gasket leaking coolant yet? You may want to get that replaced also. Check the TPS too (throttle positioning sensor) those will also cause your engine to act up