I have a 2001 TJ 3.0L with 200k on the clock. There is a rattle sound from when the car reaches around 2000 rpm. It's not always there but car does that nine out of ten times when it is cold. I suspect it to be coming from the area where belts are located.

Could it be because of tensioner pully? (I have gone through some of the discussion on this forum but not sure if that applies). Timing belt was replaced around 193k.

If it is a tensioner pully replacement, how much repair cost am I looking at?

I had a rattle at 1,100rpm and when I changed out the accessory belts it went away.
Have a look how tight the belts are and if they are in good condition.
If you're lucky all they may need is a bit of tightening

I'm going to say y pipe baffle only because I had the same issue and it was that and thus can only be that. Case closed.

Yes I'm being sarcastic. But my 99 TH with 250ishk on it lost a y pipe baffle, which went on holiday in my cat converter.

Head down to a local exhaust shop and get them to poke a camera in and check the baffle (takes about 5 mins, 4 mins are driving the car onto the hoist and raising it). Dunno what sort of repair bill you're looking at if the exhaust shop does it all, but I picked up a y-pipe from Mal (Mitsfix) and got a local exhaust shop to pop it in which was around $60.

The baffle rattle will change with temperature and load - it was louder and more noticible and thus more ghetto when it bogged down, and I was side by side with a solid object like a wall. EG accelerating in a maccas drive thru.

But check drive belts and whatever too. I'm a member suggesting crap, not a cop.

Thanks for your advice. This morning I left the car idling for about 4 to 5 minutes before taking a ride and it hardly did that rattle. I will do a thorough check up of exhaust and belts over the weekend and update you all.

You won't be able to see the issue with the exhaust as its internal, but maybe check anyway for dents/damage

I have also noticed that there is slight shuddering as well with rattling. Do I need to check any thing other than baffle in Y pipe?

Have you checked the accessory belts? When the engine is off you can press down on them and see how much deflection there is to get some kind of idea if they are on tight enough or not

I did a check up of belts tension today, which seemed okay to me i.e. around 10mm as per manual. Power steering belt had some cracks in it, so I replaced it today. However the rattling noise at 2000 rpm is still there.

Exhaust pipes looked okay from outside. Although I am not ruling out possible exhaust issue, yet I am not 100% confident if this could be problem. As per my understanding, a loose baffle gives a growling noise in the morning or when the car is accelerated.

The rattle problem in my car is worse while driving as opposed to when it is stationary. It sometimes also resists/shudders while changing gears at 2000 rpm. Today I checked rattling noise while it was stationary by accelerating it to 2000 rpm. It was there but not that loud and was without shuddering.

An update on this. I took the car to the dealer for diagnosis and fix. It turned out to be improper adjustment of tensioner pulley. No replacement required.