I have a 2000 Chevy Monte Carlo with a 3.4 liter that is stumbling and even stalling while driving. It will stall in park as well, it fires right back up and go again. It has been getting worse too.
It's not throwing a check engine light and no codes stored in the computer. I've replaced the Intake gaskets fuel filter and fuel pressure is at 45 psi. Plug wires, ignition module, O2 sensors, TPS, IAC valve, MAF, temp and knock sensors and fuel pressure regulator are all new.
What else should I check or look at?

 

I'd suggest revisit your vacuum hose's. What you post to me, is a vacuum leak, and not a small one.

 

I hooked up a vacuum gauge to it and it reads 14-15 inches of vacuum. According to the gauge that indicates late ignition timing. I checked all the hoses and they are good. Would this be caused by a cam or crank sensor going bad?

 

45 psi fuel pressure is low, and 14-15 in is also low, what rpm are you reading the vacuum? I still stick with a vacuum leak.