My truck is carbureted and has been running very.

My truck is carbureted and has been running very rough, so I have to baby the gas pedal to get it to go or it will bog down. I have to do the same when im at stop lights or it will shut off. Sometimes it will act normal. I have changed the fuel filter and an O2 sensor. This has been going on for months now. Doesn't get any better or worse. Sometimes after I have been driving for a considerable distance and I shut it off for a few minutes and then start up to go again, I have to bay the gas again to get it up to higher rpms, I smell a very strong gas odor. Every now and then when im to impatient and it will not start and I have to wait 15 to 20 minutes, I put a few ounces of gas in the carb which always does the trick. With all of that being said, is their a small pump on the top area of the carb that could problem or are their going to be 15 other solutions that it could be and I just have to go down the line til I fix it. There it is I'm all done bitching, so. Any solutions or suggestions?