The 3:31 kid in "Uncle Dickie's Happy Funshine Hour" was Scrappy in disguise.
They sound similar. Scrappy is shown to have an affinity for pranks in this version, though the two we see onscreen are both directed at Dastardly somehow. Maybe he thought that Dastardly resorting to getting innocent kids involved was a bit much (as he might not have even expected the Wacky Races crew to go for the wholesome programming regime) And tagged along in disguise to keep an eye on Dastardly's poor audience. And he was the kid who threw the tomatoes, in case you were wondering. I.Q. Ickly is the grandson of Professor Pat Pending.
The reason he decided to start racing is because of his admiration towards his grandfather, from whom he gets his love for gadgets and racing. Ickly's mom, seen in a couple of episodes, is also a very intelligent inventor, suggesting that she may be Pat Pending's daughter.