Dodge Repair: Dodge Intrepid 99 3.5L

Question
Hi, I own a 1999 Dodge Intrepid with a 3.6L engine. For a few months now it has been dying randomly while driving or at idle. When we are finally able to start it again, the cruise control and air conditioner turn on, which I assume are fully computer controlled. We have taken it to a mechanic who says it may be the alternator belt and wants to charge $350 for the initial repair. I can easily drive it short distances without trouble but we are avoiding driving it as much as possible right now. What would be your advice on where I should start? Thank you very much.

Answer
Hi Brandon,
I believe that you have either a 3.2 or 3.5L engine.
The best approach is to find out any fault codes that may be stored in the engine controller. It may be possible to use the ignition key to do that: "on-off-on-off-on and leave on" doing that in 5 seconds or less elapsed time. Then watch the odometer window in the cluster to see the mileage reading be replaced by any 4-digit numbers preceded by a P. Let me know if that works. Otherwise, a nationwide auto parts store such as Autozone will often do a free code readout using a plug-in code reader, or a shop will do it for $40 or less. Get the code numbers, ask what they mean, and then let me know and we'll figure out what to do next.
Don't pay for any repairs or buy parts till you have the code(s). I suspect it will be something fairly simple but the fault code is needed to know exactly what to replace.
Please read the PS below and respond to it.
Thanks,
Roland