I have a 92 Bonneville SE. I originally had a problem starting the car on the first or even 2nd turn of the key. Sometimes it would fire up just fine and others it just wouldn't. Now it has gotten worse with other things now happening. Now it needs at least 3 turns of the key to start up, the first two sometimes 3 it will just crank but not start and when it does actually start it seems to start rough. If I kick down the accelerator it will idle fine afterwards. 2 new things now are happening. First one, if I let it idle (when the car is warm) if I give the accelerator a little kick (to about 1500 rpm) and let go of the throttle it will drop below 500 rpm and generally die out (this has happened several times). The second thing is that if I drive at low speeds (example driving out of a parking lot at about 10 mph) it would die on me, I would put it in park and it would fire back up. Any ideas?

How many miles? Replaced anything relevant recently?

I always like to pull the vacuum line off the fuel pressure regulator on the end of the fuel rail real quick to see if it'* dry inside. If gas comes out, the regulator is leaking, and sucking fuel into the vacuum lines. This can cause the symptoms you describe.

I haven't replaced anything as of yet. 138,000 on the mileage.

I went out and checked the codes, it cycled like this: 1 flash pauses 2 flash (code 12) diagnostic working. Second was 2 flash pause 3 flash (code 23 Intake air temp sensor low temp indicated). Third 5 flash pause 8 flash (code 58 ??? don't know what 58 is). Each code was repeated 3 times before it moved onto the next and then just recycled after all 3 codes. Anyone know what code 58 is??? Also could this be part my problem mentioned above?

IAT Sensor: Check the back of your air-filter box to see if the sensor has become accidentally disconnected.

Code 58 means that the fuel enable signal to the computer is being lost. The signal comes from the Pass-Key II system.

This code requires a good diagnostic because it signals an electrical problem. The problem could be anywhere in-between the resistor pellet in your key and the PCM. It could also be bad connections at the battery.

Here'* some info to read:
http://www.bonnevilleattitude.com/fo...opic.php?t=665
http://www.bonnevilleattitude.com/fo...opic.php?t=664
http://www.bonnevilleattitude.com/fo...opic.php?t=307
http://www.bonnevilleattitude.com/fo...opic.php?t=304

Ok, found out the lead to the airbox sensor was disconnected. I pluged it back in, disconnected battery for about 20 min and reconnected that. No more codes. (did that last night). Today noticed it started a little easier, but don't think problem is fixed. So here is what I think I am going to do. Gonna start with plugs (NGK), wires (MSD), I think I will changes the Coils as well (MSD), however should I change the ignition module as well?? Will that make a difference?? Also gonna change the fuel filter. Future mods will include K&N System, Exhaust and Chip. By making changes to the ignition system will this require any changes with the chip right away or is this something I can do before I switch the chip??

One other question ... with the airbox sensor, when going to a K&N system, what will happen with this sensor?