I drive my Montero on weekends for mountain biking and snowboarding in big bear CA and have been looking to improve my truck. (2.6 L manual, with Lsd)

1. There is a whining noise when I let off the clutch in neutral and while driving?

2. The idle RPM is not exactly pinned at 1000 100% of the time and sometimes flucuates 100 or 200 rpm in traffic while idling? (The spring to the throttle broke and I sort of Jimmie rigged it on there for now) After this, the truck seems to be accelerating better, how tight does the spring need to be?

3. There are squeaking noise from the rear and front end. For example, if the truck is parked I can physical push down on bumper and make a squeaking noise that is loud and annoying especially pronounced when driving with stereo off.

History: I have owned for 4 yearsà ODM reads 263,000

I got the engine rebuilt 2 years ago which included a new clutch set and they said they resurfaced the flywheel. At the same time the Carb was overhauled and also a radiator core rod out.
I have been replacing the oil every 3-4 K with fram filter ( will change to OEM next time) and Castro GTX 10w 40.. My Montero seems a little underpowered perhaps a new cat convert. Will help?

In addition, I was considering using some carpet insulation at home depot because the original hood insulator is gone Thus all bear metal.

Any comments and suggestion are greatly appreciated I have learned so much off of the forums and am a big fan of these vehicles.

1. I THINK this is your throwout bearing. Someone else can probably confirm.

question 2 - i think you're idle should be more like 750-800. Make sure your throttle return spring on the carb is strong enough to be pulling the throttle plate all the way down to the idle screw every time. But not too hard so you're ankle gets a workout. Unsteady idle can be caused by a lot of things though. try googling for unsteady idle or surging idle.

3. This is not surprisign given the miles. I have the same thing occasionally. I think its caused by dirt and mud piled up in old leaf spring bushings. Fix the problem short term by power washing out the mud and applying some lubrican to the bushings. Fix it right by replacing the bushings.

also, the idle fluctuation... when does it happen? Does it drop when you let the clutch out? Do you have AC?

#3 When was the last time the 17 zerk fitting were greased? It could also be bad shocks.

1. it has to be the throw out bearing, mine had the same simptoms and I had to replace it.

3. I agree, grease or shocks

Good luck.