Feul or ignition problem?

90 S10 Blazer 4.3 6 cyl 187,000 miles
2 months ago I changed feul filter because it wasn't running smooth. Now it almost seems like the same thing is happening again. It was running fine then started chugging again. Would only go about 10 mph with the gas pushed all the way to the floor. I could get it to start after that but ran really rough. I can hear the feul pump running with key turned on. Also I took the feul filter loose and turned the key on to see if any gas would pump it did but not with that much pressure. Could it be the filter again the gas that came out looked pretty dirty? In the TBI it looked like only one side was getting feul. It almost starts but just doesn't.