Okay, so I got a '96 RS from my dad. He bought it from a guy in another state and it's missing the front bumper ground effect thing. When I drive the car above 65 or 70 mph, it starts to sway when I let off the gas. I've had people tell me it's a motor mount, I've had people tell me it's my suspension, and I've finally had one person tell me that the reason it sways is because of the missing piece of the ground effect/body kit thing. I wanted to know if it was possible for the lack of that piece to make the car sway.

I'm also going to eventually post pictures of my car on here, but I need to get her detailed and cleaned up a bit on the outside first.

 

I can tell you it is not due to the ground effect. Whomever told you that knows nothing about cars, I'm assuming. Does it sway real fast, or is it shaky when said conditions are met?

 

Check for excessive slop in your tie-rod ends, too much play in the front wheel bearings, or excessive play in the steering in general. Also check for a broken sway bar end link. When you back off the gas, body weight transfers towards the front end. It's possible that's making your front wheels do the shimmy-shimmy-shake.

 

Alright. It's a slow sway, almost as if I'm floating in air... If that makes sense.
But thanks for the replies so far, I kind of expected to get nothing.

 

Floating, eh? Then check your front struts. If they are badly worn or dead, your front tires will be bouncing up and down as you hit bumps in the road. That will make the front end skiddish (float and drift).