Hi, my 2000 Impala suddenly stalled on me today driving down the road at about 40. I restarted and then it died again. I limped home. I tried starting it again and it would start but then the RPM's would hunt around (go up to 1400 then drop to 800 and then up to 1000) and then it died (check engine light was on as well). Once it cooled off, I restarted it and it ran completely fine to Advance Auto where they were nice enough to run the diagnostic code. It was a P0300 or 'Random Multiple Cylinder Misfire Detected'. Then I tried to start the car to go home and it died again. I made it halfway home and then it wouldn't start. A nice Police officer pushed me (with her patrol car believe it or not) into a neighborhood. It sat for about an hour and then it started up again and ran fine for about a mile and a half and then started dieing on me again. So it seems like it doesn't start having problems until it gets warmed up. Also, I can smell gas when it finally quits and won't keep running.

 

Have you replaced your spark plugs and wires at all? Id at least give that a try since you know is a misfiring issue.

 

Yup, replaced plugs and wires about 8 months ago. Probably about 10,000 miles ago.

 

The thing that stands out here is that you can smell gas right before it dies... So I am guessing that your plugs may not be gapped correctly... if the gap is too narrow you wont create enough spark to ignite the fuel. Try pulling one plug out and double check the gap to make sure that it is the right specs for your engine. You should be able to get the gap info in the owners manual, or online.

 

I have had a similar problem with my '04 Impala. The FIRST mechanic diagnosed it as a bad MAF sensor ($139.00 reman + $87 core at Autozone) or perhaps the Crankshaft Position Sensor. No joy. The SECOND mechanic replaced the Catalytic Converter, plugs and wires ($510.00). No joy. The THIRD mechanic is the dealer. Intake manifold gasket and fuel filter. $882.66. Not even a dent. I refused the vehicle and they drove it for about a quarter mile before determining the fix hadn't worked. Now its a cracked rear bank exhaust manifold. Another four hundred bucks. And the part is on backorder till tomorrow. Bottom line: Good luck!

 

Ok, so I read on another post on this site or another forum, can't remember, that you can unplug the mass airflow sensor and if the car runs fine after that it was the issue. So, i waited for the thing to die on me again. I pulled over and unplugged the sensor. The car started right up and ran fine. So, I bought a new mass airflow sensor and Im good to go. Thanks for the posts. I also got turned on to gmpartsdirect.com. Great prices for genuine gm parts. Straypooch, ive heard of some folks getting bad reman MAF sensors. You might want to unplug yours and give it a go without it. As i understand it, the car will use other sensors and should run ok if that was your issue.