Nissan Repair: 1994 nissan clutch replacement and rough idle, clutch replacement, fuel injector cleaner

Question
My 94 Altima seems to need another new clutch and I want to order an OEM part as I've had the clutch replaced twice in the last 30k miles after previous clutch went at least 65k miles(i bought the car with 70k miles and replaced clutch at 135k and again at 148k and now have 160k miles on it).  If I take a clutch kit to a mechanics, how many hours should it take to install?  i want OEM part so think i should get them myself. Is that nuts?
secondly...the car is idling very rough and rpm's are at about 600-650 at idle and car shaking at idle and having a rough start in first.   seems to be unrelated to clutch issue..i have used fuel injector cleaner and change oil regularly...otherwise the car runs great and gets decent mileage.  is this related to clutch or another issue?  any thoughts greatly appreciated!
so..need idea of labor cost for clutch replacement

Answer
Hi Alice -

For your Altima clutch replacement is 5.2 hours. Just got to find a reasonable but competent mechanic. OEM is good, however just know that the installers will probably not guarantee the work as far as parts are concerned.

For the idle, 650 is way too low. It needs to be adjusted up to about 800 to 900. there should be an adjustment screw on the intake throat.

Hope this helpa -
aloha
calvin