car runs rough in cold
 

alright this is my friend's car and he came into my work and asked me what i thought, i told him i wasnt sure so i would post on here.

he says his car, when its cold, will start and run, but will not rev past 2000 rpm. he has to cut his car off, cut on his vtec (i assume he has a vtec controller) runs it to 3k and cuts the car off, when he cranks the car back up, then it runs great. i dont know what to tell him. he has a sohc 90 crx. i told him maybe some kind of air intake temp sensor, but i havent messed with a sohc motor, so im not sure. lemme know if anyone knows what the hell it could be, thanks in advance