I recently got the PF .70 MM TB installed on the VI that's mated to the VQ35 heads and block. I noticed, when sitting at stoplights for a little while the RPMS will drop a little bit and the engine will start vibrating shaking, as soon as I give it gas it goes away, and also after a little while it goes away it does it for maybe 10-15 seconds max. I adjusted the TB and the IACV to really no avail besides idle adjustment. What can I check for? I do not hear any vacuum leaks, and don't see anything out of the ordinary.

 

Do you have poly or filled mounts? My car does that only at certain rpm though and it gets annoying. But with the added stuff maybe your car feels like its doing it more than usual? Do you notice a flux in rpms?

Could also be a bad mount.

 

I just got a brand new rear OEM mount, but I know they are weak. Anthing else I can check for?

 

How would I know if it's electrical or mechanical, I have no SES light or anything.

One thing to note, when I unplug the brown sensor, the SAFC-II reads 100% throttle and the idle goes up to like 1500-2000!!!, as soon as I plug it in, all is good.