Very hard to start when cold have to crank over for long times trys to fire on one or two runs ok when started but when using some throttle belches black smoke

Causes can be numerous so here is some reading material which may help you track down your particular issue..........
Crank No Start

I doubt it.
Sounds more like a weak spark or fuel problems.
Have you tried using starting fluid, and can you verify a strong spark at the plugs ?

old post. but will answer.
the starter only cranks the engine, that is it's only job.
if it cranks robustly (at crank shaft pulley ,see it) then its ok.
250 RPM is typical cranking speed. RPM
no starts are complex.
for any engine Gas, to start you needs 4 things.

1. ALL FUSE TO EFI GOOD, TEST THEM. CEL glows key on?
2. full engine compression and crank vacuum 5" HG or more.?>??
3. Spark , try a fresh tune up with fresh spark plugs. all 6 sparking.?
4. Fueling , must be right. not flooding , not starving

if spark and engine are good, all engines(most) will start with test fuel.
This one simple test. proves the engine is ok, and spark is ok.
and the fuel system is dead.
these checks , will let is work the 4 systems. that might fail.
this is the classic basics path.
and works 99.% of the time.

exceptions, are clogged melted cat.
or stuck wide open EGR
or ISC stuck closed, (no starting air.) use 10% throttle to prove that.
or flooding, if flooding use super secret unflood mode (opr guide)
hold the throttle (right foot) pedal to the floor, this cuts fueling
and the flooded engine starts, for full time or runs and floods and stalls again.
This is called basics , in all ASE books in print.
RTM.

sounds like a fuel problem, may have water in the gas or needs a fuel filter , try a bottle of drygas before the filter

When is the last time you had a tune-up on your truck? During the cold winter months, if the battery does not have a proper level of cranking amps it is sometimes hard for the engine to turnover in the cold. You may need a tune-up or battery replaced.

I would get a multimeter on the crank sensor and check the wave pattern I believe there is a issue with timing or the crank sensor.

You need to replace your starter. This is an old problem with GM starters, the armature gets older and then starts to swell when it gets warm.

sounds to me like your check valve in fuel line is not working. If you have the original lift pump it located in there.

When you turn the key to start position that 2 or 3 times does starter click? or does it do nothing? If it clicks starter selanoid on starter is bad, If it don't click at all its ignition switch thats bad.

Welcome to the forum. Your question has to many variables. Cold weather out here in Cen Cal this time of year is mid 40s. Is the problem when the vehicle is cold as in ovrernight but starts ok when it is warm? Does it crank OK but seem like it's not getting fuel? If you hold the throttle slightly open, does it start OK?