Stalling van starts fine some days?

Lets run the codes to see if any are stored, this guide can help:

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

On the days it will not start can you use starting fluid, and it starts? We need to find out if the problem is fuel released or an ignition system problem, please go over this video to help us see what's going on:

https://www.youtube.com/watch?v=lXLJbuAZ4CE&t

I have seen the catalytic converter fail apart internally and cause this issue but there should be a code for it if this is the problem. Please go over these guides and get back to us.

DId this problem start after the fuel pump installation? I have seen crankshaft angle sensors start to go out and cause this issue. Also, can you tell me what the coolant sensor reading is from the scanner? I have seen these sensors get weak and cause mixture problems. Please go over this guide as well

https://www.2carpros.com/articles/engine-cranks-excessively-before-starting

Please go over this guide and get back to us.