93 GMC Z71 - rough start or sometimes won't start unless it sits for a while (hours). When it does start it smells of gas and usually is accompanyed by smoke coming out of exhaust. Replaced fuel filter, checked injectors and pressure seems okay. It will run fine for few days but then boom it gives me a hard time. 5.7L any ideas/suggestions would be AWESOME!

I'm assuming "white" smoke and not "black" since you didn't mention.
If white smoke, it's coolant or oil leaking into the cylinder heads while it is not running.
If oil and from leaking valve guide seals, it's not a serious thing and basically a nuisance. Just keep your motor oil level topped off until you have new seals installed or dispose of vehicle.
If coolant, it's a much more serious problem. The liquid in the head will do two things. One, foul the spark plug and possibly cause hydraulic lock (fluids cannot be compressed and cylinder locks up)
Check you oil level and if keeps going down a quart every few hundred miles, it's the valve seals.
Check your coolant. If down, it's possibly a head gasket leak, which is not uncommon for vintage and make.
If coolant keeps going down and not leaking on ground, that's a smoking gun, not to make a bad pun, for a leaking head gasket. At this point, it's prudent to first invest $10 on Barr's Leak Copper (looks like liquid copper in a jar) and add to your coolant system. Follow manufacturer's instructions and then see if problem either persists or abates.
If it abates, go and buy a lottery ticket since you're very lucky and solved a serious problem with an inexpensive fix.

Good Luck