Ok, if you didn't have it open much, then forget what I stated. What does your engine idle at?

P.S. Referring to post #36, a DMM also.

 

If nothing else, the new canister will probably solve the fuel smell (barring any fuel line problems). The current canister probably can't absorb the vapors, so after you get gas the vapors are going through the canister and up and out of the "AIR" hose. Common symptom for the canister.

 

Idle is around 700-800 RPM, and fairly smooth.

 

That's high. Should be 650. You may have an air leak. On your truck, the EVAP solenoid will open for SEVERE lean conditions. Normally it will not be open at idle. That might be contributing. Question is whether the EVAP solenoid being open (if it is) is the cause or effect of your lean condition?

Hook up your scanner live data and see what the fuel trims look like at idle, closed loop. If they are high (above 5-10%) hold your RPM around 2k. Do the fuel trims come down? TPS angle will be a factor also. Then hold RPM around 3k. What are the trims doing?

If the TP is barely open at 2-3K, disconnect the hose at point "A" on the diagram and seal the nipple on the throttle body. Make sure everything else is connected/installed (air cleaner, etc). What happens when you run the same tests?

If the TP is open and you still have high fuel trims at those RPMs, then an air leak or the EVAP is probably not the issue and there is something else going on causing the lean condition.

 

Here is a rough, incomplete draft of what I was working on for you. It's about 75% there and needs some fine tuning also. Just wanted to send you what I have to get your wheels spinning while we are waiting for you to get the MityVac. Once again, this is rough and I stopped a few days ago, so there might even be a change I need to make here or there...and it is incomplete.

 

Crap...forgot to mention, clear the codes before doing the steps in post #44.

 

According to my code scanner, the RPM at idle is really 650-700. The tach shows 700-800.

I cleared the code I had, and looked at the fuel trims at idle, 2k, and 3k. They are as follows :

Idle: STFT - 2.3, to - 4.7
LTFT - 7.0

2k: STFT - 19.5 to - 21.1
LTFT 6.3

3k: STFT - 7.8 to - 10.2
LTFT 4.7

Hopefully those numbers make some kind of sense to you. I'l get a mighty vac and start working through the tests you wrote up

 

Well that's completely opposite of your p0305 code. Wasn't expecting those. So your fuel trims are at that point (high end):

Idle: -11.7 (not horrible but running a little rich)
2k: -14.8 (rich condition)
3k: -5.5 (acceptable)

Something is causing a rich condition. At 2K STFT is really trying to pull the LTFT down even further (shorten the injector pulse) and eventually would.

 

The fact that at 3k RPM it's acceptable kinda goes along with how it drives. If I manually shift it, as the revs get higher, I can open the throttle farther without it stalling.

Just for grins I floored it earlier, and it completely stalled out.

 

I'd start with checking exhaust back pressure at idle and at 2k. Just to rule out a bad cat/partially blocked exhaust. Does your truck have the AIR system on it (smog pump)?