The car started fine on the way to work the other morning. I stopped to get gas, turned the car off, filled it and up, went to restart it, and deader than dead. No relay click, no lights or power at all, totally dead as if the battery was disconnected. And 4:30 in the morning, so no-one around to ask for a jump. Luckily, I was directly across the street from a 24-hour Auto Zone, so I pulled the battery and marched across the street with it. The battery was only a year old and tested fine. While removing it, I noticed that the threads on the negative battry post were stripped, so I purchased new posts while at Auto Zone. Went back to the gas station, reinstalled the battery with new posts, and the car started right up as if nothing had happened?! BUT....
It was surging and looping at idle, and running rough, hesitating like it was about to stall during the ride home. Thinking it was most likely a bad alternator, this morning I started it (started right up with no problem) and disconnected the battery.The engine continued to run with the batter disconnected, but still surging; so I'm thinking not an alternator problem? It never did this before it died that morning.
Any help would be greatly appreciated. Any suggestions?

 

Get a multimeter and check the alternator voltage while car is running.

 

I agree. I think you are in the right direction with solving this problem.

 

Is there a reason you haven't checked for trouble codes?

 

Alternator would affect charging, not the running of the engine. Measure with a external voltmeter to make sure charging voltage is steady. (A radical changing can cause a problem.)

The stalling problem sounds like a idle air control motor (IAC). But before you jump into that since it was not a problem before. Remove the battery cable for 30 seconds to reset all computers especially the PCM. Something might not have initialized correctly when you were messing around with the battery. Then try it again.

Also check the other end of the ground and positive cable for any corrosion and tightness.

 

Once you remove the battery you should restart and let it idle for five minutes to relearn the fuel injector and timing adjustments. All learned settings are lost with battery removal. Could it be that you didn't let it have time to normalize it's settings? Disconnect the battery again for ten minutes then start the car without hitting the gas pedal. Once started just let it idle for five minutes. Then take it for a spin speeding up and letting off gradually getting more aggressive with the throttle. Then take it up to highway speeds and hold it there for at least five minutes. See if that makes a difference.

 

You can also disconnect (GENTLY it is old and brittle by now) the alt's pig tail and run the car on just the new battery for a short test to see if the rectifier's diodes are indeed cross conducting and causing part of the problem.

 

The vacuum hoses that go to your cruise control unit (mounted just above the battery) can often fail due to excessive exposure to battery acid vapors. If you have a vacuum leak there..or these hoses are really soft and leave a black residue on your fingers when you check them. This vacuum issue can be a part of your problem due to it being a vacuum leak after the throttle body...where the Idle Air Control vale is located...which is the part that basically controls your idle via moving in and out and controlling a vacuum leak...so-to-speak.

Checking your voltage can be done by using your "GAUGES" button on your dash and seeing what it shows in your speedometer display area.

Hopefully you checked and made sure that your battery cable ends were CLEAN and that they are TIGHT.

Driving the car above 35 MPH will allow the IAC to reset and find its setting for the conditions that the engine is under at that time. Simply idling does not work (for me). The car needs to be driven steady for a short while....and I usually have my scanner connected so I can watch was is going on and if the engine was cold...I can see how long it takes for the engine to warm up and go into "CLOSED LOOP". AND in many cases when it goes into closed loop and it starts to "hunt" for an idle (idles up and down)...I have found that the fuel pump pressure is the problem....(too low).

DUB

 

That's Not True, If Your Alternator' Voltage Is Surging, Your Spark voltage Is Lessened, Leading To An Idle Surge As The Computer Tries To Compensate.

 

Not seeing what you have going on (condition of factory cable ends and such)...your grounds could also be the cause..or partially the cause.

DUB

 

…And as I like to point out, battery cables have TWO ends and BOTH ENDS need to be making a good connection.