91 buick century sputters from idle roll outs

[truckandbusman]

Hey all, thanks for taking the time. My sisters 91 Buick Century with a 3300 powerplant has 140000 miles, and overall it runs out pretty good. Problem is that it sputters on moderate roll out from any stop. Doesn't matter if the motor is warm or not. It needed a tune-up so the plugs, wires, fuel filter, air filter, and the oil have all been changed. The mass air flow sensor was cleaned. All the coils packs were swapped off a known good running buick. The sputtering continues. The ignition module tested bad, so that has been changed also. On a whim I even changed the gas cap, and it seemed to help, but it never goes away. Granted all these changes have made the car run better and better. Especially on the highway and in passing situations. But it never leaves a light without sputtering. It will sputter about half way through the intersection, and then all the sudden "wake up" and will run fine all through all the gears. I'm running out of ideas, so hopefully you guys will know where to point me. It isn't throwing any codes, and idles normally, and runs great after sputtering off the line. I'm not talking about heavy acceleration. Just normal driving. It will roll away from a light without sputtering if you leave out very, very slow. But normal driving conditions bring out the worst. Again, thanks for reading. Any suggestions are greatly apprecitated. Have a great day...

[wheel_man]

Sounds kinda like a problem I had before with my 91 Century. Check out this forum and try what I suggested to this other person I think it should do the trick. 91 century stalling at times

[GM Line Rat]

It sounds like a poor fuel delivery Problem.....Has the fuel pump ever been changed in this car or the fuel tank inspected for rust or a dirty fuel pump pickup screen?

Here the other suggestions under the symptom "Engine hesitates under
Acceleration" (I left out items you have allready addresed).

1. Inspect Fuel System Pressure..... Incorrect fuel pressure being delivered to fuel injection system. (Use a fuel pressure gauge, connected to the Schrader test Valve at the back of the fuel rail, test for proper fuel pressure).

2. Inspect Fuel Pump... Improperly functioning fuel pump or circuits.

3. Inspect Throttle Position Sensor - Faulty throttle position sensor or throttle position sensor circuit.

4. Inspect Fuel Tank - Contaminated fuel from rusted or deteriorated fuel tank. (If the has been ran with several tanks of gas, this would not be a issue).

5. Inspect Accelerator Pump Diaphragm - Damaged or faulty fuel injection accelerator pump diaphragm.

6. Inspect Mass Air Flow Sensor - Improperly connected or faulty mass air flow sensor. (What method did you use to clean the MAF?)

7. Inspect Oxygen Sensor - Damaged or faulty oxygen sensor or circuit. (This should have set code 13 If O2 Sensor was bad, Has it ever been changed? Recommended to change every 50K Miles).....Use AC-Delco OR Sensors only!!!

8. Inspect Fuel Injectors - Plugged, dirty or poorly connected fuel injector(s).