2003 GMC Sierra 4.3L V6 bogs down and stops while trying to crank

[Jmarket56]

I have a 2003 GMC Sierra 4.3L v6.

 

Over the last few years, the truck would crank and run fine if you drove it everyday, but if you let it sit for a couple weeks it would take forever to crank. We would have to hold the gas pedal to the floor or pump the pedal and it would finally crank. 
 

Recently it started slowly getting worse, and it started to not crank after 12-24 hrs of sitting. My dad believed that the fuel injectors were leaking. 
 

After fighting with it, I decided to change out the spider injectors. Made no difference. Changed the fuel filter just in case. No difference. After fighting with it all day, I got it to crank, but it wasn’t running the best, almost like it was misfiring but no codes. The next day it wouldn’t crank again,  I noticed one of the plastic tabs that the distributor cap screws into was missing half of it causing the cap not to sit tight and the pickups were corroded. 
 

Changed the distributor to the updated aluminum style and still can’t get it to crank. At first I had trouble getting the distributor in time, but I believe it is in time now. 
 

In the current position the truck will crank to a certain point and then stop. I changed the old battery out to rule it out, with the new battery it would crank strong until a certain point. With the distributor timed any other way, it will sit there and try to crank all day. 
 

Today I changed the spark plugs out and the spark plug wires were changed last year. 
 

During my attempts of cranking ive had a few codes pop up. At first it was the coolant temp sensor voltage, I guess the connector got damaged when I changed the injectors because it was in two separate pieces so I replaced the connector on the wiring harness. Then it was a Bank 1 Sensor 1 02 sensor, it popped up a couple times when trying to crank before changing the distributor but has not returned. Finally was the anti theft fuel enable, I believe this would pop up when the battery started getting low. 
 

Currently there are no codes present. 

I have attached pictures showing the damage and wear on the distributor 

 

Any advice on where I need to look?