cold start idle surge

Ever since I bought my teg with a B16a, whenever I start it up when its cold the engine revs up and down for a little while, then it goes away. I was wondering if anyone can tell me what it is, i think its like a sensor or the fast idle thermo valve, but if anyone can tell me how to fix it i would appreciate it. Thanks for the help.

There’s a couple of tegtips about cleaning the EACV and FITV.