I have a 95 Z71 throttle bodie. I just bought a brand new crate engine. I dropped it in and attached a set of vortec heads w/ a brand new manifold and headers. The damn thing wont crank

. Every thing is brand new except for the altenator, a/c pump, And power steering pump. I have checked the firing order a dozen times. The starter drags unesseceraly slow but it acts like it should still crank. I know its getting fuel cause i used a 1/4 tank of gas trying to start it, plus the injectors are spaying fuel and fire comes from the headers. I did however forget to ground the engine and tryed to crank it, and i got closer to starting the damn thing than after i grounded it

. Now that ive grounded it it aint hittin like it was before. What did i tear up? Also when it does hit it back fires through the throttle bodie and catches fire for a brief second

. I set the valves the way Haynes said to?!? One more thing now mah starters fuckin up when i turn the key it just klicks and i lose all power to every thing and i have to dis- and re- connect the battery to get any kind of power. It kinda started doin that all of a sudden cause it
WAS workin fine(slow tho). Can any one help me i am so fed up with this

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