2000 Pontiac Bonneville stalls and hard start

Is the check engine light on? Have you checked fuel pump pressure? Also, do volts drop before it dies or while or after?

If the voltage drops before the engine, it sounds like it is related to the electrical system, but that could also include an electric fuel pump that is bad. What I need you to do is when this happens, check fuel pump pressure to make sure it is working properly. Here are directions for checking it:

https://www.2carpros.com/how_to/how_to_check_fuel_pressure.htm

You will need a fuel pressure gauge. Most parts stores will lend or rent them to you.

Let me know what you find.

Joe

Then it has to be an electrical issue. My only thoughts at this point is a bad fuseable link between the lat and battery.

I have to be honest, it's hard to estimate how long they will take to track it down. As I mentioned, I feel it is related to a fuseable link. When you take the vehicle, tell them the battery and alt are good. You had them checked. As a result, you feel it is related to a fuseable link.

Hopefully, they will start there and it won't take as long.

Let me know what you find.

Joe

I'm sorry. Typing too fast. Lat is actually alt.

There is a chance you got a bad one. Check this page out and follow the steps in checking it to see if that is actually the problem.

http://www.adriatic-company.it/matizclub/tecnica/manualeII/M31f3%20Engine%20Controls%20152-279.pdf

The PO336 is the first code and provides step by step instructions on how to check the system for that code. Let me know what you find.

Joe