1996 Cadillac Deville

Engine Performance problem
1996 Cadillac Deville V8 Four Wheel Drive Automatic 145300 miles

I have a '96 sedan deville. Every now and again, the accelerator will get stuck and I will be going faster without even pushing the gas pedal. Once I put it in park, it'll jerk really hard like its trying to go, then it will have this really loud sound like I'm pressing the gas while I'm in park. I tried spraying WD-40 on the inside under the hood but it only stops temporarily. What part controls the acceleration and what do I need to fix it?
May 12, 2008.

Clean out the throttle plates with carb cleaner and an old tooth brush first

May 13, 2008.