I recently purchased a 2003 hyuandai tiburon GT with 171k miles on it i was on the interstate doing 80 mph in 4th gear at around 6k rpm when my clutch pedal dropped back into the floor board and just stuck. had lotta slipage over the past week before this happened.. do i need to replace the clutch or do a flywheel conversion.

500 is too low for and automatic in drive
normal idle is 850-900 and should not drop below 800 in drive as the ECM should be adjusting for the drive load when in gear
take it in to an accredited service shop that works on your make of vehicle and have the problem diagnosed properly and quote

Fyi....I know this post is several years old but if my answer can help someone it's worth it. I took my car to the dealership today for literally this EXACT problem on my 2010 Scion xB with 125k miles. I read this post and was shocked to read that someone else's xB was behaving the same way under the same conditions. In 4th gear at around 38 MPH and 1500 RPMs I get a vibration and a noise that, like the OP said, sounds like you're going over a rumble strip. That's the perfect wat to describe it. The dealership told me that it needs a torque converter. They want to charge me a thousand for the part and another thousand for labor because they've got to take the whole transmission out of the car and it's going to take 2 days (really 9 hours, they said, but they'd be keeping the car 2 days). I'm currently calling around to see if ANYONE can do it cheaper, but just in case anyone else comes here looking for an answer to this question, I hope this helps. Torque converter might be your problem.

sounds like 'flaring' of the auto, maybe a service at the auto shop will fix it.

the rpm's can vary from car to car , it all depends on the gearing in the transmission and ratios, 4.0 does seem high for a V6 the easiest thing would to be have your transmission serviced , on this car you need to get the Idle Air Control checked, In all the forums Ive read on this car , that seems to be whats wrong when the RPM's seem to high, also if you have the automatic trans and an electronic manual shifting mode does it do the same thing when you have it in the manual mode? there has been lots of discussion also on the MAP sensor,, I would suggest you have the OBD codes read to see if its listing any trouble codes within the computer that can help with locating your answers, once you get those codes if you post the results here, people will help you and explain what they mean, If you reply to this feed by replying, I will look them up for you

yes but you can get it less becauses the kit cost only 72 to220$ for it and its a half day labor onit any ? you can call 863 261 6116 if no answer leave a message

The slave cylinder for your clutch has a valve in it, which keeps the clutch from engaging too quickly. The purpose is to keep you from just dumping the clutch and wreaking havoc on your transmission. If you're confident that you don't need that extra safety device in there, you can remove it, just google slave cylinder valve removal. It will give your clutch more of an aftermarket feel.

56k just about due for 60,000 mile srvice. When you take it in have the problem reviewed. Good uck.New trans fluid might do the trick. Good Luck, Ned

definitely something in the tranny

More maintenance history needed. Oil changed regularly, timing belt replaced at 60 K miles, Engine air filter & intake air hose inspection?
Causes of the problem you describe are many. Recommend you have a technician check your throttle position sensor for any bad spots in the potentiometer... most likely cause when there is NO Check Engine light.

That is normal,If you do the same speed in 4th gear the rpm's will almost double.

The rpm's will repond faster in a manual than an automatic.

In a manual the engine supplies the power required directly to the gear that you have selected thus the engine rpm's will increase or decrease as needed.