HELP - Heat Pulsating Problem

I need help again. I've encountered a rather discomforting problem in the last few weeks. When ever my truck gets warm after a drive, she starts to pulsate. She jerks real bad, and at points if I don't release the gas, she starts to choke. When I pull out of parking lots is the worst. And I can't get speed out of her? Someone please help me! Engine is a 302, and it's a 91