Intermittent shuts off just after started

First thing you need to check is when you start it and it stalls, leave the key in the run postion and see if the theft light or security light is flashing, if it is then this would indicate a anti theft problem.

Sosunds like its possible that the idle air control valve is not working, thats why it will keep running when you press on gas. This is a real tough one to try to help with due to not witnessing condition. If you can get the truck to autozone they can scan the computer and get us the trouble codes if there is one. They scan them for free.

No, not unless you have a scan tool as we will need to attempt to communicate with the module in order to try and find out if there is an issue. Basically if the check engine light never comes on when you start the vehicle then that normally means the PCM has failed. So if they scanned it and it had no codes then that is different then if they could not communicate with it.

I suspect they were not able to communicate with it so if that is the case then the PCM is most likely going to be the issue.

Does your snap on tool monitor live data? Hopefully it does so we can monitor the throttle position sensor when this is happening. I understand it appears you replaced it when you say throttle body sensor. Also when you cleaned the IAC we need to probably replace this depending on what we find.

A torque converter can cause the vehicle to stall when coming to a stop but not when it is just idling. Think of this as a manual transmission and when you come to a stop with it in gear and you don't push the clutch. As long as the vehicle is still moving it keeps running. It is when you finally come to a stop or just before it that the engine stalls. A TC staying on is the exact same idea.

Let's start with monitoring live data if possible and go from there. If we can't then we will try to do some basic testing but since you mentioned the scan tool, this will be the easiest way.

Feel free to get a video of the screen when this happens on these sensors rather then trying to write them all down. Thanks

The way to try and confirm an IAC on this engine is to hold the accelerator open just a touch when this happens.

As you can see from the attachment, the IAC just bypasses the throttle blade to control air flow. So if this is the issue and the IAC is sticking closed not allowing enough air into the engine then cracking the throttle will correct this.

You could be onto something with this because I initially discounted this because you said you cleaned it and that usually at least make a change to the issue. However, re-reading your issue that it is fine when you hold the accelerator seems to prove this out. Clearly it is not definitive but if it were me, I would replace the IAC based on this info.

Okay. Do you have easy access to that scan tool from your friend? If so, we need to monitor a couple things. We need to look at o2 data when it is stalling or getting ready to stall. We need to see if it is going lean when stalling. Either look at the short term fuel trims or o2 voltage.

Also, here is a guide that will run through the other common causes. Let me know which of these we have not addressed and we can chase that down when we see what the o2 sensors are reading when it is stalling. Thanks

https://www.2carpros.com/articles/engine-stalls

I am not sure I know which line you are talking about however, if it is a vacuum line and not just a vent line then it can definitely be an issue. At least it is not something that we want to ignore. Maybe get a picture of it and that will help.

Also, the fuel pressure dropping that quickly doesn't sound normal so I am sure you are on the right path.

Does this issue happen more after filling the tank? Does it start and then stall almost immediately?

Okay. The issue by itself definitely sounds fuel related so if that line going to the regulator is "leaking" then that could be all the issues less the EVAP codes.

Basically I think you are on the right path with your plan. Please let me know what happens and we can go from there. Thanks