Hey all i just got my first RX and gotta say its bitchin, its a 88' GTU got it for 900$, everything works good and well it runs fine lots of power (compared to my 4cyl truck) but when u press the gas pedal it has a loud kud sound like u just hit a big pot hole and the car kinda lurches a tiny bit and then does the same thing when u let off the gas pedal, it almost seems like its the limited slip engaging and disengaging or something but REALLY REALLY loud, i took my girlfriend for a ride and she freaked out and thought we hit something the first time it happened, any ideas on exactly what it is.

Most likely its one of your diff mounts... get a flashlight, lift the back of your car to check it out. Might also be your struts, but they just kinda clunk around... the don't really cause any drivability impairment.