1995 Chevy Truck Chugging (possibly the fuel pump?)

I have a 95 chey 1500/w 350 TBI, when I am driving usally at any speed when I take my foot of the throttle and then slghtly put steady pressure back on it the truck starts chugging and jerking. It does it wether your going 10mph or 60mph. If you are sitting idleing and hold the rpm's to 1000, or driving slow 10-15 mph it starts loping and sounds like its missing or has a BIG cam in it. I thought bad plug wires but the were under warrenty so got new one and didn't fix the problem. So now i'm thinking its the fuel pump but not sure why that would cause this? Theres not really a easy way to check fuel pressure/w TBI is there? Don't pumps usally work or not work? Any thoughts would be great! Thank you in advance!