Rpm and weird sound when accelerating

[sunbeam]

Try using the highest octane gas available, try a bottle of the redline injector cleaner, go for a long drive on the highway, change the oil.

Also double check the oil level is not too low or overfilled.

It could also be increasing the revs as the ac pumps engage, this may be especially happening on hot days or when not moving fast (less cold air), especially if the coolant is super old or of unknown age.

Could it be an obstructed fuel pump? If rust/debris/whatever else interrupts the fuel supply? More senior member would probably have a better idea. Like others have said hard to tell.

Sometimes my car "whistles" a bit, have not considered this an issue but it could be a normal sound?

[Fummins]

Whistling isn't normal for a car. Coolant has absolutely nothing to do the the air conditioner. Try wearing a blue suit.

[Akafrosty]

I will definitely try the injector cleaner, yeah it's super weird it never does it when I'm driving only when I am stationary at a red light and the AC is on, and it's definitely not the whistle because I know that's usually the belt which I have already changed and I use for synthetic oil change it on a very consistent basis. I also have three other Mitsubishi Mirage, and none of them do it I run a car rental service

[Akafrosty]

I'm not sure I know how to post a YouTube video but I will figure it out but when I'm stationary at a red light in the AC is on my RPMs will fluctuate from a normal 750 to a 500 and go up and down

[Fummins]

I usually have to re-tighten belts after replacement. They're quiet at first then stretch a hair and sometimes squeak a few days later. At least I find that with the Gates brand belts. It's relatively normal for the rpm to change when the ac kicks in. I don't know that 500-750 is normal cause I never pay attention.
If it squeaks when the rpm drop then have your belt tightened up, or do it yourself with a 12mm anything.

[Akafrosty]

I have no problem with my belts at all , my problem is my rpm ,car feels like it's about to turn off then goes back up to 700 and back down to 500 until I turn off the AC

[Fummins]

My bad, reading is hard. I was going back and reading the first post thinking it was you...
There were a few people that had their ac compressors or the clutch for the compressor fail. It was more common in the southern states where you'd have nicer weather irc. The compressors do lug the engine down a lot though. If I have to pull out into traffic I just shut the ac off cause it sometimes turns the car into super slug mode.

[Akafrosty]

Yea I was thinking maybe the AC comp , and yea I'm in Los Angeles

[Eggman]

Fouled throttle body?

[7milesout]

Maybe the weird noise while accelerating is the front tires losing traction and sliding across the pavement due to all the torque?