1987 suzuki gs550e stalls when i get ready to move in first gear?

i bought this bike over the weekend. the guy said it was run from time to time but never ran regular for about 5 years. i rode the bike home from where i bought it about 1 1/2 hrs away. it ran fine like a dream with no issues even on the highway doing 70. the following day i went to take it out to ride it and it started giving me problems anytime i come to a stop sign or stop like and start to come to a stop it stalls. my idle was alittle low so i moved it up a hair bc i called the bikeshop and they said to try that first. still the same issue it starts and idles up fine as soon as i try to take off it stalls now. i cant get moving at all. i ordered new plugs oil oil filter and air filter to replace them. does this sound like a gumpped up carb since it sat so long bc he filled it with premuim before i got it or does it sound like i need to adjust the clutch up by the lever?? it doesnt jump or buck or grind when i go into gear as soon as i let off the clutch that is when it starts to bog down and just stall. i read alot of different reviews with a 1000 different answers so any other insite to this bike would be great thanks