Vehicle vibrates at 650 rpm

[OGHalo]

Hello from Canada, I drive a 05 Toyota Hilux Surf with the 2.7L 2TR-FE, I noticed for a while that once the vehicle is warm up, idling around 750rpm in drive while stopped it would drop to 650rpm and make a vibration noise for a bit and the engine would vibrate as well and would jump back to 750rpm with no vibrations, at one point when I had a catch can install to the pcv it was loud with it on when it drop to 650rpm, I clean my throttle body, maf, spark plug and change the air filter which helped my stalling issue but not my vibrating issue, no lose of power or mpg. Idk if its a vacuum leak or something, Any ideas?

 

[TacoKen]

If it only does it at idle, possibly injectors need cleaning/flushing. Also could be a/c compressor cycling and if bad causing an extra load. If it only does it when you first put it into gear it may be transmission issue.

 

[OGHalo]

If it only does it at idle, possibly injectors need cleaning/flushing. Also could be a/c compressor cycling and if bad causing an extra load. If it only does it when you first put it into gear it may be transmission issue.

I noticed it when I have the a/c on more so then having it turn off all together, I checked the transmission fluid and the dip stick was on the line for hot when the vehicle was on cold and after warming it up it was on the same line, it's a bit darker red then normal and not sure when the fluid was last change so I will change the fluids to see if that makes a difference first

 

[TacoKen]

I had a similar problem with my daughter's Ford Focus. Had a rough idle and when you turn the a/c on it would worsen as the compressor put a strain on the motor. Turned out to be the transmission mount was bad. Might check motor and trans mounts also.