Did you ever hook up a scan tool and pull any codes?
I know hard to diagnose on here, but are you aware of what a EVAP Canister does? Because what it does if the purge leak valve is stuck open it will cause a lot of the problems you are having. Do you have rough idling too?
Here is what it does it traps and recirculates fuel vapor so that it can be used as fuel for the engine and prevents polluting the environment (The smell of fuel you are talking about). The canister has a purge solenoid and is the component responsible for purging the EVAP system by that switch allowing fuel vapor to get into the engine.
You get engine problems when that purge valve is stuck open and creates a vacuum leak which you know is really going to effect how your engine is running. What happens then is this will change the vehicles air to fuel ratio and cause rough idling being like bouncy when running and causes difficult starts. Then you say you turn the key 2-3 times and that is energizing your fuel pump to put pressure, giving fuel to the engine to start up. See what I mean by this EVAP can and a vacuum leak? Or maybe your can is bad too being rotted out.
Does that sound like what yours is doing? With what you changed and not sure if you pulled codes with what you are saying this could be the problem.
If you do not have a scan tool I would take it some place and let them pull some codes. I know O2 sensors can cause problems too, but you didn't mention having like really bad fuel mileage. Plus, with its age those never hurt to change too due to if you take it in they will charge you a fortune. I think they are like maybe 50.00 each and their is an up flow (top) and down flow (bottom), being 2 of each on each side of the truck. They do make a special tool like always, but on my 2005 I had to use a wrench due to GM put the exhaust pipe way to close to get this "cut out" socket in.
They are super easy to get at, but be ready and have a pipe that can fit over the wrench for leverage when and/if you change them. I just disconnected my battery and cut the wires so I could get the wrench over them for more grabbing power verses the cut off side only grabbing it on two sides.
Now saying you are doing this but throwing this out there. We all know that liquids do not compress and air and vapors do. I see people getting gas clicking away getting as much as they can and IMHO with it being so full it is putting to much pressure on this EVAP can where it can be in the filler spout and tank.
