360 shakes

I am also having this problem with a my truck start her up and she shakes slightly then as she worms smooths out when i push the throttle on the carb she revs very smooth when i get in the cab, Park and Neutral are smooth for the most part but in reverse and drive has a jerking shaking idle and when i accelerate its like a broken washing machine rattling everything worse in low RPMS but still bad in high, have many people telling me this and that and even though i am a rookie with autos, they are stupider than i am telling me its my alignment! no no... but it is a 360 rebuilt don't know what was in it before......was told broken 360.....Any advise would be greatly appreciated!