Moped Army

so here's the skinny, starts fine and will run to full throttle but only when there is no resistance on the rear wheel, like when it's on the stand

if i sit on my ped and try to ride it'll either go about 5mph or just shut off... my transmission fluid is fine, getting fuel, spark, compression is good, i was pulled over for having a crooked plate and the cops were asking me moped questions and the one was "does this thing require a lot of maintenance" and i said yeah but i haven't had to do much in the past 1,200 miles... then it broke about half a mile after that

i think i jinxed myself, what could cause this kind of issue