V6 to 5.7 LS1 in an 02 Sierra

I've done a V6 to V8 swap on a 2002 GMC Sierra. I rebuilt the 5.7 and installed a T/C 220/230 cam with 116 degree lobe sep. The truck idles good and shifts fine, throttle response is crisp in Park/Neutral, but acts like a choked chicken when you apply a lot of throttle in drive. If this were a carb'd engine with a distributor, I'd say the dist. rotor arm was broken or the timing was 1 tooth off. When I initially started the motor, I did the crank relearn procedure to clear the P1336 code. I did this again last night (misfire code set) to see if it would help and I made things worse. I can hear what sounds like leaky exhaust but it's coming from the intake manifold, which tells me the intake valve hasn't completely closed before the cylinder fires. This sounds like a timing issue to me. Also when you hold the throttle open and the engine revs you hear popping back through the plenum. Again, timing issue.
Needless to say, I'm at a loss and need some help from some of the more knowledgeable/experienced LS folks.
I posted the tune file on the HP Tuners forum if you would like to look at it.
Would appreciate any suggestions or hints.

sounds to me like a fuel issue, lean. Either there is a huge vacuum leak somewhere or you don't have enough fuel pump feeding the requisite 52-58 PSI of fuel pressure at the injector rail.

I should have thought of that. Was going by ALLdata specs that said V6 pump supplied 60-66 psi. So had it in my head that pressure was OK. But if the regulator is messed up, who knows what's on the manifold. I'll check that today. Thanks RHB.

Pressure is 55 to 62 lbs.

have you had the PCM reprogrammed since you changed the camshaft?

Yes I have.

Anyone have any other ideas? Any suggestions appreciated!

Sounds like it's pinging... what octane fuel are you running? With that LS1 you should be running at least 91 octane.

No, not pinging. 92 Octane.