99 Suburban starts and dies, starts, backfires, dies again

It sometimes will start and die as soon as it is moved into either drive or reverse. It starts right back up just to die again. Sometimes it backfires too. If it is acting like this and I can getting it driving at a slow speed (5-15mph) it will keep dying out. When I accelerate hard and get it going faster the engine runs stronger and will not die out. It will do fine until it is shut off and restarted. I just had a full tune up done on it last month and that did not help. Any ideas what the problem could be? It doesn't do this all of the time. Sometimes it starts and goes just fine with no problems.

Does it set any codes or turn the Check Engine light on? Autozone will hook a scan tool up if you don't have one and they won't charge a dime to do it. Might want to take a look at catalytic converter.It sometimes will start and die as soon as it is moved into either drive or reverse. It starts right back up just to die again. Sometimes it backfires too. If it is acting like this and I can getting it driving at a slow speed (5-15mph) it will keep dying out. When I accelerate hard and get it going faster the engine runs stronger and will not die out. It will do fine until it is shut off and restarted. I just had a full tune up done on it last month and that did not help. Any ideas what the problem could be? It doesn't do this all of the time. Sometimes it starts and goes just fine with no problems.

What mileage and what engine?
Might want to look at dist cap and roto for moisture or cracks or carbon tracking and check plug and coil wires.
Any spark jumping around under hood or snaping in dist cap?
Check for good hot blue spark to all plugs.

And always confirm good full fuel pressure?

It has 115,000 miles and the 7.4L engine. The cap and rotor were changed out last month and so were the spark plugs and wires. The coil wire was removed and I was not told that there was any damage to it. There is no spark jumping or snapping. How do I check the fuel pressure? The check engine light is not on.