Ok, here is what i have and what ive done. I have a 1992 Trans am 5.0 TPI, 319,000 original miles, daily driver, stock except for recently changed out injectors to Bosch III's 19#.
Was driving great, then the original GM ICM died. I changed it out for a cheap autozone one to be able to move the car. When i changed that, it would backfire and pop through the exhaust really violently when i revved high and let off.
The new ICM died within the week so i replaced the whole distributor and ICM (got a good deal on a brand new GM RamJet distributor). Replaced it the right way with making sure the rotor was facing the correct way when i installed the new one.
Now that ive replaced the distributor it takes a while to start, cranks for a while and usually wont start until i turn the key for a second time.
I dont think both issues are related since it was backfiring before it was hard to start, but im not sure
I dont know if it is fuel pump related, i will say the pump does whine sometimes when its hot out and ive been driving on the high way for a while.
The car is my daily driver and i drive it about 35 miles a day back and forth to work. Still drives great in normal driving and on the highway but i have noticed a small loss in power.

 

Sounds like the timing may be off. Did you put a timing light on it to verify?

Old saying I use a lot:

Trust, but verify. Verify, verify, and then verify, then you can trust it.

 

Yeah I made sure it's right at 6 degrees. I even tried 8 and 0 to see any difference but I didn't notice any.

 

Did you have the 'set timing' connector disconnected when you set timing? (sorry, had to ask.)

 

Yup, made sure of that
It starts just fine when it hasn't been sitting for too long