So, I'm not 100% sure what I'm suppose to be doing it, so I'm gonna wing it. I didn't have time to get an excellent screen showing all tasks due to deadline and school and stuff, so I snapped a couple, then picked the best. I'm listing all tasks but if some can't be verified due to shotty screenshotmanship, I understand.
Duff Man - Party Down at Church (just plain wrong to pelvic thrust in front of a church)
Nelson - Shoot BBs at car to take out his aggression (wrath)
Snake - Rob Kwik-E-Mart (Greed)
Apu - Pray to Ganesh (idolatry)
Mr. Plow - Eat key to city (gluttony)
Shauna - Send flirts on Springface or whatever it is (lust)
Dr. Hibbert - sacrifice his principles (sloth, maybe)
Comic book guy - Cosplay (envy - wants to be someone else)
Quinby - Embezzle money (greed)
Krusty - Inflate important (pride)
Barney - Go on a binge (gluttony)
Hank - test famethrower
Moe - smuggle endangered species (greed/stealing/smuggling)
Edna - smoking (gluttony)
Smithers - drunken wreck (gluttony)
Burns - hide nuclear waste (greed)
Grandpa - napping (sloth)
Bumblebee man - I'm going with stealing honey :P (greed)
Bart - skipping school (sloth)
Martin - try to be cool (pride)
Dr. Nick - Street pharmacy (drug dealing/greed)
Ned - power walking (vanity aka pride)
Otto - sleeping it off (sloth)
Ken Brockman - Relaxing with alcohol (gluttony/sloth)
Cletus - Digging through garbage (greed)
Sideshow Mel - juggling to gain money (greed)
Hope I got everyone. I didn't list Moleman intentionally because I didn't think I'd get points for him. Otherwise, anyone I may have missed was unintentional.