Hey Jeff, don't give up just yet. I think the problem may be with a 'heavy' throttle and not a slipper clutch or terrain issue.
Slipper Clutch adjustment will help later down the road when racing, not when backyard bashing. The slipper clutch should be tight enough so that you are not hearing it squeel when taking off (depending on terrain). I would investigate that more later on once you get the control.
I would try the street first, it helped me years ago. Granted you will eat up your tires but it helps you become familair with the truck. If you are in the yard on dirt or grass, try not to squeeze full throttle when taking off, ease into it and work on any oversteer/understeer just like you would a real car .
It takes practice and knowing when to juice it and when not to. There are TONS of people I race with that make me look like a rookie when it comes to handling my car on a new track!
It's all about having fun. If you let it frustrate you, you might as well be at work, right?
If you want to feel good about how well you are driving, buy the kids one! You'll think you're a pro in no time!!!!!
My daughter T-Bones the mailbox with her Pede on every trip to the yard!
Remember, it's just a toy...until you win with it.