I just bought a rx7 tt from japan and recently have had a couple problems, one is when cold i have to keep my foot on the gas to keep running and when warm the rpms go from 400 to 1200 surging back and fourth, the second is when im in any gear and i give it a little bit of gas it revs up and then picks up speed a few seconds later and rpms go back down and car rumbles any help would be appreciated these problems just started and wasnt doing it when i first got it

 

Probably an EGR issue. Doing an EGR delete is reccomended, if it is in accordance with your state laws. I was having the same idling issue, and it fixed mine. The EGR delete can be a complicated thing though, so make sure you know what youre doing. There should be a good amount of threads on here concerning that