72 C10 Original 402 Stalling

[brmartinitz]

I am new to owning a vintage vehicle and trying to learn and have abit of fun. So please bear with me if I am not using the correct language to explain the situation.

In the past when cold I would pump the foot feet a few times and it would start right up and idle above 7500 until I hit the foot feet to idle the choke. When warm I could just turn the ignition switch and it would start and idle at 7500.

The other day I was driving and noticed a bit of sluggishness when I began to accelerate from a dead stop, but appeared to be ok at higher speeds. The sluggishness got continually worse over the next 30 minutes of driving until the vehicle would die at stoplights. To get it restarted I had to put the foot feet to the floor, leave the foot feet to the floor, turn the ignition switch until it started. To keep the engine from not stalling I had to keep the engine above 12500 plus. So at stoplight it was foot on the brake and accelerator or put it in neutral and keep the engine above 12500 plus.

Thoughts? Recommendations on what might be the problem? Much thanks.