Car not running right advice

[chrisxr2]

Right car is constantly misfiring/ hesitating (Sounding like a tractor) throughout the rev range. Sometimes dieing at junctions, sometimes stuck at between 2500 and 3500 revs no changing down or anything makes a difference you have to pump the accelerator just to keep momentum at all. have changed the fuel filter, cleaned the carb and jets to no avail, the car seems fine when first driving then as it gets warmer gets worse. Has not been right sice it died on the way home a few weeks ago. Think maybe the rolling road is my best tool to use but wonder if anyone has any ideas first?? Very frustrating 44 mile round trip to lincoln today. All the obvious things have been eliminated. I am sure it is something simple but what else can people suggest??
2.1 pinto with twin webers. I dont think enough fuel is going through when you watch the fuel filter, any advice would be greatly appreciated. Car has not had any issues for previous 7000 miles so no clues there.