hello everyone. i have a 76 280 w/carb that had been running great until recently when it started chocking after 2nd gear goes in. i step on the pedal and it will not accelerate.the pedal just goes deeper. i have a few ideas of what i can be but i want to know for sure. i have not replaced to air filter, fuel filter so i was thinking that those would be the first things to take care of first. i would like to know any suggestions from our mb experts out there. thanks.