Cold start getting better

I've been able to start the truck now 2 times with out starting fluid but it takes a while. I find that if I turn the key to on and then of several times and then with out touching the gas pedal it will start and then die after 10 or 20 seconds. If I keep doing this for 3 or 4 minutes it will eventually start. once warmed up it starts no problem. Wondering if it is a fuel pressure issue that I loose it after it sits. I read on one post that the pump doesn't run in the on position but does in the start until the engine starts and then the ecm will kick in and run the relay. Once it's running everything seems to be as it should.

Update, if I don't touch the gas pedal it starts and idles for a couple of seconds and dies. If I push the gas pedal it dies quickly. If I keep starting it eventually is starts

Have you looked into the throttle position sensor at all ? Perhaps try an adjustment and see if it makes any difference.

I had similar problems when the engine was cold. I replaced the TPS and it made an amazing difference.

Last night I pulled the plug off and checked for ground and that was OK, then put the plug back on and put a paper clip in he center wire and turned on the key and adjusted it to .5v and that all went according to the book. I still have the code 15 so I'm stumped.