New engine for my Z71.... Help !

I just finished replacing my 350 with the new Vortec 350 (330 hp) Everything went well I thought. The new motor is missing a beat, sounds like a popping from exhaust. Timing is about 12 degrees ahead,new high rise intake,750 TBI.  The truck is a 93 GMC Z-71.. After market chip to match motor.  EGR is all hooked up,replaced mod in dist.,replaced fuel filter,performance chip and its fastttttt BUT if I just touch the gas a little there is a big hesatation but if I nail it to the floor, the hesatation is there but only for a fraction of a second. ohhhhh yeaaaaa I had the intake bored out to match the 750TBI. Im running out of ideas. (and money) I also have it about 10 degrees ahead on timing. Seems to be the best there. Any more ideas? Thanks !

Oh Yeaaaaa What should the spark plug gap be? Remember its 330 hp crate engine.

Any Ideas ?????? The first 1/2 inch is when it seems to bog down. after that,its smooth sailing from then on. It also seems to burning alot of gas. (going by the gauge) No smoke or bad fumes though. Thanks !