transmission 2014 Silverado 1500. Should I start with transmission problems or fuel system problems?

[ayoes52]

So I have a 2014 Silverado with the 5.3 and if I don't let it idle while fueling I can't start it for atleast 20-30 minutes (whether I put half a tank or full tank) I had the fuel pump changed and that temporarily fixed it for about 3 months.  So then I changed the injectors and fuel sensor there was no change and no check engine light.  

 

Probably unrelated but its saying gas cap open when its closed and has started messing up on shift points with a weird whine almost like its stuck in tow-haul with an engine brake when I start slowing down.  I don't know how else to explain it other than that.  Transmission was replaced by dealer at 78K it's sitting at 115K now and if I could I'd drive it off a cliff at this point but SW Texas has no cliffs.  I've heard possibly torque converter, whole transmission, or simple computer problem and was wondering what y'all might think.  Why I ever switched out of the Duramax and Allison I don't know but lesson learned.

 

 

[davester]

Have you considered reading engine codes even though the check engine light isn't on?

[ayoes52]

1 hour ago, davester said:

Have you considered reading engine codes even though the check engine light isn't on?

Yea it threw the faulty oil pressure sensor code PO521 or something I believe and had it replaced even though the gauge was working fine.  Dealership couldn't get anything else to pop up.  I'm just at a loss on it and tired of paying the dealership to guess. I figure there's more knowledge on here than the dealership.