Rough Start, Black Smoke!

Son Of a B,
Haha, its one problem after another on this rebuild of a 1988 chevy V10 blazer 4wd. It has a 8cyl. 350c.i.d. TBI. motor in it. When I start the motor, it runs at low 200-400rpms. Then after the black smoke slowly goes away it idles back up at around 700rpm. I think there is an oil leak in the heads. I think because there are bad valve stem seals. But wouldn't oil leakage cause blue smoke?

I was thinking it was dirty fuel goin into my Throttle body. But, I recently rebuilt my throttle body, put new fuel filter on, new gaskets, even new o rings for the fuel injectors. I ran codes, all that came up was code 44 Lean exhaust, obviously, so I do not know where to go from here.

Also, I noticed oil is leaking from the valve covers so im gonna put new gaskets on, but i dont think that would have anything to do with black smoke coming out.

Any advice is good advice!

Blue smoke is oil
Black smoke is to much fuel
White smoke is coolant
Things that i would check would be, IAC on the pass side of throttle body (it could have a peice of carbon stuck in there) next i would do a compresson test on all cyl to make sure that you don't have a low one ( that really messes with the computors mind and it don't know how much fuel it needs) ....
On my truck i had a broken intake valve spring so the valve would stay open and blow back into the intake and that really screwed the computor up and it just dumped fuel in to the motor. Good luck and keep us posted.

ok well this is what i found, after smelling some kind of fuses while running the truck, i noticed oil was leaking from the valve cover. i replaced the gasket and the leak stopped and the code went away and so did the black smoke.

could the computer try to regulate the vacuum leak with more fuel going into the cylinders, Thus creating black smoke?